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  • Fixed Effect Regression

    Hi guys,
    I'm new to Stata and to this forum. I've got tennis data from ATP matches and I want to run fixed effect regressions. The two basic regressions I want to run are: 1) https://gyazo.com/994caa3fd252bc7cd084df5e47612c54 2) https://gyazo.com/c8d5d321fe6e98283a851975165e4d79
    I want to check what can affect the effort that tennis player exert. Effort, which is measured as P, is the number of games a tennis player won in a specific match. I assume that the more games won in a specific match, the more effort the player exerted. HET is the heterogeneity between the two tennis players, measured by the difference in their ATP ranking. Spread is the prize spread for the current round between the winning prize and the losing prize. X should be a set of tournament dummies. My dataset contains, for every single match from 2013, tournament characteristics like surface, which type of torunament (Grand Slam, Masters, ATP 250, ATP 500), etc. I want to control with tournament fixed effect and year fixed effect. For the second regression, there is another variable called "numoftourneys" in which I want to measure the intrinsic motivation of every player. This variable means how many tournaments a specific tennis player participated in a specific year. Now, of course some top tennis players will not participate in the minoric ATP 250 tounaments, and respectively weak players won't play Grand Slams because these tournaments are way out of their league, so in order to control on this difference, I thought about running also a player fixed effect.
    However, I truly don't know how to specify those models in Stata. I read about fixed effect modelling in Stata but it made me even more confused. All I did so far is converting string variables to numeric variables, using the egen (group) command. Any help will be much appreciated.
    Last edited by Luca Toni; 04 Jul 2022, 08:48.

  • #2
    Luca:
    welcome to ths forum.
    You seem to have a panel dataset.
    What I'm not clear with your description is whether your -panelid- is players or tournaments.
    In addition, an example/excert of your dataset via -dataex- (as per FAQ) coulf help enormously.
    Kind regards,
    Carlo
    (Stata 18.0 SE)

    Comment


    • #3
      Originally posted by Carlo Lazzaro View Post
      Luca:
      welcome to ths forum.
      You seem to have a panel dataset.
      What I'm not clear with your description is whether your -panelid- is players or tournaments.
      In addition, an example/excert of your dataset via -dataex- (as per FAQ) coulf help enormously.
      Hi Carlo!
      Thanks for your kind words. Can you explain the difference for whether its players or tournaments?
      My dataset has many columns and rows (I have 37000 observations from 2013-2021). There is a restriction on the number of columns so I will copy only a small part of it. I can also send you entire file in email if that helps you.
      Also, some variables refer to both players, like individual heterogeneity (favourite will get a negative value because of the ATP ranking and underdog will get a positive value. Example: rank 1 plays against rank 80, individual heterogeneity for the favourite is -79 and for the underdog is 79), and some variables refer to both players, meaning only ~18500 observations (example for such variable: heterogeneity in *absolute value* in the match, in order to check the *total* effort in the match and not the individual effort of each player).
      Now it's your turn

      Code:
      * Example generated by -dataex-. For more info, type help dataex
      clear
      input str44 Tournament int Year str49 TournamentYear str5 Surface str3 Nationality str24 IndividualPlayer byte GameswonbyIndividualPlayer int IndividualHeterogeneity double PrizeSpread1000 byte NumOfTourneys
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "NED" "Haase R."           3  -82              8.838 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SVK" "Klizan M."         10   17                  . 21
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "UKR" "Davydenko N."      12    9                  . 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "CYP" "Baghdatis M."      12   26                  . 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "NED" "Sijsling I."       17   69                  . 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "GER" "Kamke T."           5   51                  . 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "RUS" "Youzhny M."        13  -93              8.838 21
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ARG" "Del Potro J.M."    12  -49             17.405 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "NED" "De Bakker T."       7  121                  .  9
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "POL" "Janowicz J."        9  -39              8.838 18
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SLO" "Zemlja G."          4   62                  . 14
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ARG" "Del Potro J.M."    12  -34             38.076 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SVK" "Klizan M."         16  -24              8.838 21
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ITA" "Viola M."          17  111                  .  4
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ESP" "Granollers M."     11 -111              8.838 22
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Paire B."           7    2                  . 25
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "BUL" "Dimitrov G."       15   -4              8.838 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ROU" "Hanescu V."         4   26                  . 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SUI" "Federer R."        12 -121  8.144000000000002 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SUI" "Federer R."        12  -62              8.838 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "NED" "De Bakker T."      14   93                  .  9
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "GER" "Brands D."         10   88                  . 18
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Benneteau J."      12  -26  8.144000000000002 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FIN" "Nieminen J."       17  -69  8.144000000000002 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "BUL" "Dimitrov G."        8   34                  . 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Benneteau J."      13   25                  . 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ROU" "Hanescu V."        13   39                  . 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Benneteau J."       9   32                  . 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "GER" "Mayer F."           5   -9              8.838 21
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Benneteau J."      12  -51              8.838 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ARG" "Del Potro J.M."    12 -100              8.838 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "LAT" "Gulbis E."         12   82                  . 18
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SVK" "Klizan M."         12  -46  8.144000000000002 21
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Mathieu P.H."      15   24                  . 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "CYP" "Baghdatis M."      16   -5             17.405 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "UKR" "Davydenko N."       8   -4  8.144000000000002 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ARG" "Del Potro J.M."    13  -32            189.135 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ITA" "Viola M."           4  131                  .  4
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "GER" "Bachinger M."      13   69                  .  4
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Gasquet R."         8  -26  8.144000000000002 21
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FIN" "Nieminen J."       12    7                  . 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Simon G."          10  -25             38.076 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Benneteau J."      13   37                  . 19
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ARG" "Del Potro J.M."    13 -125  8.144000000000002 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FIN" "Nieminen J."        7   49                  . 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "BUL" "Dimitrov G."       19    5                  . 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "BEL" "Goffin D."          0   -7              8.838 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "CYP" "Baghdatis M."      16   -2              8.838 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Monfils G."         7  100                  . 18
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "NED" "Sijsling I."        6   46                  . 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "BUL" "Dimitrov G."       13    4                  . 20
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "LAT" "Gulbis E."          9  125                  . 18
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Simon G."          13  -88              8.838 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "AUS" "Tomic B."          12    4                  . 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "ITA" "Seppi A."           7 -107              8.838 22
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Simon G."          12 -131  8.144000000000002 17
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SRB" "Troicki V."         7   30                  . 15
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Tsonga J.W."       16  -69              8.838 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Gasquet R."        13  -30              8.838 21
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "SUI" "Federer R."         8  -37             17.405 16
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "GER" "Bachinger M."      12  107                  .  4
      "ABN AMRO World Tennis Tournament" 2013 "ABN AMRO World Tennis Tournament 2013" "Hard" "FRA" "Simon G."          15  -17             17.405 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GER" "Kohlschreiber P."   9  -37 18.868000000000002 22
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "POL" "Janowicz J."       12    8                  . 23
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "FRA" "Tsonga J.W."        8  -27              8.833 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GBR" "Murray A."         12  -29              9.584 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CRO" "Cilic M."          12   31                  . 20
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "LAT" "Gulbis E."         13    5                  . 20
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "NED" "Huta Galung J."    13  -56              9.584  3
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GBR" "Murray A."          7  -31 18.868000000000002 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "NED" "De Bakker T."      16  131                  .  4
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CZE" "Berdych T."        12  -30            205.134 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CZE" "Rosol L."           4   13                  . 23
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "BUL" "Dimitrov G."       10   -5              8.833 18
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "NED" "Sijsling I."       14   37                  . 22
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "NED" "Sijsling I."       12   27                  . 22
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CRO" "Cilic M."           6   30                  . 20
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "POL" "Janowicz J."       15  -19              9.584 23
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GER" "Kohlschreiber P."  13  -63              9.584 22
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CZE" "Berdych T."        12  -17 41.288999999999994 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GER" "Haas T."           20  -20              9.584  9
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CZE" "Berdych T."        12  -24              9.584 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "FRA" "Monfils G."         9   19                  . 15
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GER" "Berrer M."          3   83                  .  4
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "BUL" "Dimitrov G."       13   -9              9.584 18
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GER" "Kohlschreiber P."  14   18                  . 22
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "FRA" "Tsonga J.W."       16  -20              9.584 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "RUS" "Tursunov D."       12    9                  . 16
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "FIN" "Nieminen J."       14  -77              9.584 20
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CZE" "Berdych T."        12  -37              8.833 17
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "RUS" "Youzhny M."         4  -49              9.584 19
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "CRO" "Cilic M."          12   27                  . 20
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "FRA" "Roger-Vasselin E."  6   29                  . 24
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "GER" "Mayer F."          10   20                  .  7
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "FRA" "Mahut N."          13  -25              9.584 20
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "AUT" "Thiem D."          13  107                  . 21
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "ARG" "Del Potro J.M."     7  -20 18.868000000000002  4
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "NED" "Sijsling I."       12  -83              8.833 22
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "FRA" "Gasquet R."        10  -18              8.833 14
      "ABN AMRO World Tennis Tournament" 2014 "ABN AMRO World Tennis Tournament 2014" "Hard" "LAT" "Gulbis E."          5   17                  . 20
      end
      .

      Comment


      • #4
        Luca:
        your dataset needs some surgery before being analyzed (basically, turning -string- into numerical variables).
        In addition, the -fe- estimator wipes out all time-invariant variables (hence, it is nit the way to go with your data exerpt).
        Eventually, you have -repeated time values- withn panels; this is in not an issue, as long as you -xtset- your dataset with -panelid- only. Thisn fix comes at the cost of making time-series operators (such as lags and leads) unavailable.
        A toy-example follows:
        Code:
        . encode Tournament, g(Tournament_num)
        
        
        . encode Nationality, g(Nationality_num)
        
        
        . encode IndividualPlayer, g(IndividualPlayer_num)
        
        . xtset IndividualPlayer_num Year
        repeated time values within panel
        r(451);
        
        
        . xtset IndividualPlayer_num
        
        Panel variable: IndividualPlayer_num (unbalanced)
        
        
        . xtreg PrizeSpread1000 i.Year  i.Nationality_num , fe vce(cluster IndividualPlayer_num)
        note: 4.Nationality_num omitted because of collinearity.
        note: 5.Nationality_num omitted because of collinearity.
        note: 7.Nationality_num omitted because of collinearity.
        note: 8.Nationality_num omitted because of collinearity.
        note: 9.Nationality_num omitted because of collinearity.
        note: 10.Nationality_num omitted because of collinearity.
        note: 11.Nationality_num omitted because of collinearity.
        note: 12.Nationality_num omitted because of collinearity.
        note: 13.Nationality_num omitted because of collinearity.
        note: 14.Nationality_num omitted because of collinearity.
        note: 16.Nationality_num omitted because of collinearity.
        note: 17.Nationality_num omitted because of collinearity.
        note: 19.Nationality_num omitted because of collinearity.
        note: 22.Nationality_num omitted because of collinearity.
        note: 23.Nationality_num omitted because of collinearity.
        note: 24.Nationality_num omitted because of collinearity.
        
        Fixed-effects (within) regression               Number of obs     =         52
        Group variable: Individual~m                    Number of groups  =         25
        
        R-squared:                                      Obs per group:
             Within  = 0.0029                                         min =          1
             Between = 0.0351                                         avg =        2.1
             Overall = 0.0030                                         max =          6
        
                                                        F(1,24)           =       1.01
        corr(u_i, Xb) = -0.2640                         Prob > F          =     0.3248
        
                             (Std. err. adjusted for 25 clusters in IndividualPlayer_num)
        ---------------------------------------------------------------------------------
                        |               Robust
        PrizeSpread1000 | Coefficient  std. err.      t    P>|t|     [95% conf. interval]
        ----------------+----------------------------------------------------------------
                   Year |
                  2014  |  -5.928077   5.897357    -1.01   0.325    -18.09962     6.24347
                        |
        Nationality_num |
                   BEL  |          0  (omitted)
                   BUL  |          0  (omitted)
                   CYP  |          0  (omitted)
                   CZE  |          0  (omitted)
                   ESP  |          0  (omitted)
                   FIN  |          0  (omitted)
                   FRA  |          0  (omitted)
                   GBR  |          0  (omitted)
                   GER  |          0  (omitted)
                   ITA  |          0  (omitted)
                   NED  |          0  (omitted)
                   POL  |          0  (omitted)
                   RUS  |          0  (omitted)
                   SUI  |          0  (omitted)
                   SVK  |          0  (omitted)
                   UKR  |          0  (omitted)
                        |
                  _cons |   21.51101   2.381625     9.03   0.000     16.59558    26.42644
        ----------------+----------------------------------------------------------------
                sigma_u |  14.070488
                sigma_e |  44.698113
                    rho |  .09015832   (fraction of variance due to u_i)
        ---------------------------------------------------------------------------------
        
        .
        As an aside, please note that it's never the turn of interested listers to do research on posters' behalf (I'm sure that it was not your intention, but statement like that one can be misunderstood).
        Kind regards,
        Carlo
        (Stata 18.0 SE)

        Comment


        • #5
          Originally posted by Carlo Lazzaro View Post
          Luca:
          your dataset needs some surgery before being analyzed (basically, turning -string- into numerical variables).
          In addition, the -fe- estimator wipes out all time-invariant variables (hence, it is nit the way to go with your data exerpt).
          Eventually, you have -repeated time values- withn panels; this is in not an issue, as long as you -xtset- your dataset with -panelid- only. Thisn fix comes at the cost of making time-series operators (such as lags and leads) unavailable.
          A toy-example follows:
          Code:
          . encode Tournament, g(Tournament_num)
          
          
          . encode Nationality, g(Nationality_num)
          
          
          . encode IndividualPlayer, g(IndividualPlayer_num)
          
          . xtset IndividualPlayer_num Year
          repeated time values within panel
          r(451);
          
          
          . xtset IndividualPlayer_num
          
          Panel variable: IndividualPlayer_num (unbalanced)
          
          
          . xtreg PrizeSpread1000 i.Year i.Nationality_num , fe vce(cluster IndividualPlayer_num)
          note: 4.Nationality_num omitted because of collinearity.
          note: 5.Nationality_num omitted because of collinearity.
          note: 7.Nationality_num omitted because of collinearity.
          note: 8.Nationality_num omitted because of collinearity.
          note: 9.Nationality_num omitted because of collinearity.
          note: 10.Nationality_num omitted because of collinearity.
          note: 11.Nationality_num omitted because of collinearity.
          note: 12.Nationality_num omitted because of collinearity.
          note: 13.Nationality_num omitted because of collinearity.
          note: 14.Nationality_num omitted because of collinearity.
          note: 16.Nationality_num omitted because of collinearity.
          note: 17.Nationality_num omitted because of collinearity.
          note: 19.Nationality_num omitted because of collinearity.
          note: 22.Nationality_num omitted because of collinearity.
          note: 23.Nationality_num omitted because of collinearity.
          note: 24.Nationality_num omitted because of collinearity.
          
          Fixed-effects (within) regression Number of obs = 52
          Group variable: Individual~m Number of groups = 25
          
          R-squared: Obs per group:
          Within = 0.0029 min = 1
          Between = 0.0351 avg = 2.1
          Overall = 0.0030 max = 6
          
          F(1,24) = 1.01
          corr(u_i, Xb) = -0.2640 Prob > F = 0.3248
          
          (Std. err. adjusted for 25 clusters in IndividualPlayer_num)
          ---------------------------------------------------------------------------------
          | Robust
          PrizeSpread1000 | Coefficient std. err. t P>|t| [95% conf. interval]
          ----------------+----------------------------------------------------------------
          Year |
          2014 | -5.928077 5.897357 -1.01 0.325 -18.09962 6.24347
          |
          Nationality_num |
          BEL | 0 (omitted)
          BUL | 0 (omitted)
          CYP | 0 (omitted)
          CZE | 0 (omitted)
          ESP | 0 (omitted)
          FIN | 0 (omitted)
          FRA | 0 (omitted)
          GBR | 0 (omitted)
          GER | 0 (omitted)
          ITA | 0 (omitted)
          NED | 0 (omitted)
          POL | 0 (omitted)
          RUS | 0 (omitted)
          SUI | 0 (omitted)
          SVK | 0 (omitted)
          UKR | 0 (omitted)
          |
          _cons | 21.51101 2.381625 9.03 0.000 16.59558 26.42644
          ----------------+----------------------------------------------------------------
          sigma_u | 14.070488
          sigma_e | 44.698113
          rho | .09015832 (fraction of variance due to u_i)
          ---------------------------------------------------------------------------------
          
          .
          As an aside, please note that it's never the turn of interested listers to do research on posters' behalf (I'm sure that it was not your intention, but statement like that one can be misunderstood).
          Thanks for you answer, Carlo. I actually already converted the tournament, nationality and individual player variables to numeric (you just don't see it because I didn't choose them for this example).
          Why can't we generate tournament fixed effect? all the papers I've read in this field used it. Why do I need the i.Nationality_num? Prize spread is also not what I want to measure. I want to measure the number of games an individual player won in a specific match ("GameswonbyIndividualPlayer"). Nationality is supposed to be an explanatory variable (I want to check whether there are cultural differences among players).
          I'm very confused.
          Last edited by Luca Toni; 05 Jul 2022, 00:59.

          Comment


          • #6
            Luca:
            1) please share your data example/excerpt ready to go. If you choose to go -string-, it increases the time interested listers should devote to your query (and this could hamper more than help your chances to get helpful replies);
            2) you can easily add -i.Tournament- in the right hand-sied eof your regression equation;
            3) in the very same fashion, you can change the regressand in my toy-example as you like;
            4) the -fe- estimator will not give back a coefficient for nationality unless the player changes during the timespan the panel stretches over.
            Kind regards,
            Carlo
            (Stata 18.0 SE)

            Comment


            • #7
              Originally posted by Carlo Lazzaro View Post
              Luca:
              1) please share your data example/excerpt ready to go. If you choose to go -string-, it increases the time interested listers should devote to your query (and this could hamper more than help your chances to get helpful replies);
              2) you can easily add -i.Tournament- in the right hand-sied eof your regression equation;
              3) in the very same fashion, you can change the regressand in my toy-example as you like;
              4) the -fe- estimator will not give back a coefficient for nationality unless the player changes during the timespan the panel stretches over.
              1) In this regression I don't think I need player fixed effect, only tournament and year fixed effects: https://gyazo.com/994caa3fd252bc7cd084df5e47612c54
              2) However, in this regression (https://gyazo.com/c8d5d321fe6e98283a851975165e4d79) I also need player fixed effects because of what I wrote in the first post. NumofTourneys is an explanatory variable that measures motivation (motivation = how many tournaments a specific player participated in a given year). I want to control on the fact that very weak players can't participate top tournaments, and also superior players won't join "weak" tournaments like ATP 250. So I need to distinguish between those situations by player fixed effect, in order to get the pure impact of their motivation on the effort they exert. Is it correct?
              3) From what I wrote in 1) and 2), does it mean that xtset will be in 1) torunament and in 2) xtset will be individual player?
              Also, how can I present the results in a more convenient way? I mean like the same way in papers where they present in one table all the regressions and below it is written, for example, "Fixed Effects" "Yes" or "No", etc... How can I do it in Stata? I don't want all these "omitted" rows, obviously...

              This is what I get when running regression (2)...
              Code:
                    
              . encode Tournament, g(tournament)
              
              . encode Nationality, g(nationality)
              
              . encode IndividualPlayer, g(individualplayer)
              
              . xtset individualplayer
              
              Panel variable: individualplayer (unbalanced)
              
              . xtreg GameswonbyIndividualPlayer IndividualHeterogeneity IndividualPrizeSpread1000 NumOfTourneys SpreadNumOfTourneys i.individualplayer i.tournament i.Year, fe vce(cluster individualplayer)
              note: 2.individualplayer omitted because of collinearity.
              .
              .
              note: 648.individualplayer omitted because of collinearity.
              note: 649.individualplayer omitted because of collinearity.
              note: 650.individualplayer omitted because of collinearity.
              note: 651.individualplayer omitted because of collinearity.
              note: 654.individualplayer omitted because of collinearity.
              note: 655.individualplayer omitted because of collinearity.
              note: 656.individualplayer omitted because of collinearity.
              note: 657.individualplayer omitted because of collinearity.
              note: 658.individualplayer omitted because of collinearity.
              note: 659.individualplayer omitted because of collinearity.
              note: 660.individualplayer omitted because of collinearity.
              note: 661.individualplayer omitted because of collinearity.
              note: 662.individualplayer omitted because of collinearity.
              note: 663.individualplayer omitted because of collinearity.
              note: 664.individualplayer omitted because of collinearity.
              note: 665.individualplayer omitted because of collinearity.
              note: 666.individualplayer omitted because of collinearity.
              note: 667.individualplayer omitted because of collinearity.
              note: 668.individualplayer omitted because of collinearity.
              
              Fixed-effects (within) regression               Number of obs     =     37,060
              Group variable: individual~r                    Number of groups  =        654
              
              R-squared:                                      Obs per group:
                   Within  = 0.2642                                         min =          1
                   Between = 0.3731                                         avg =       56.7
                   Overall = 0.2701                                         max =        509
              
                                                              F(0,653)          =          .
              corr(u_i, Xb) = 0.0431                          Prob > F          =          .
              
                                                                    (Std. err. adjusted for 654 clusters in individualplayer)
              ---------------------------------------------------------------------------------------------------------------
                                                            |               Robust
                                 GameswonbyIndividualPlayer | Coefficient  std. err.      t    P>|t|     [95% conf. interval]
              ----------------------------------------------+----------------------------------------------------------------
                                    IndividualHeterogeneity |  -.0049322   .0003348   -14.73   0.000    -.0055897   -.0042748
                                  IndividualPrizeSpread1000 |    .003734   .0015154     2.46   0.014     .0007583    .0067097
                                              NumOfTourneys |   .0344991   .0070374     4.90   0.000     .0206803    .0483178
                                        SpreadNumOfTourneys |  -.0003388     .00011    -3.08   0.002    -.0005547   -.0001228
                                                            |
                                           individualplayer |
                                              Ajdukovic D.  |          0  (omitted)
                                                  Albot R.  |          0  (omitted)
                                                Alcaraz C.  |          0  (omitted)
                                                Almagro N.  |          0  (omitted)
                                             Altamirano C.  |          0  (omitted)
                                               Altmaier D.  |          0  (omitted)
                                                  Alund M.  |          0  (omitted)
                                               Amritraj P.  |          0  (omitted)
                                               Anderson K.  |          0  (omitted)
                                               Anderson O.  |          0  (omitted)
                                                Andreev A.  |          0  (omitted)
                                                Andreev I.  |          0  (omitted)
                                              Andreozzi G.  |          0  (omitted)
                                                Androic T.  |          0  (omitted)
                                                Andujar P.  |          0  (omitted)
                                                Aragone J.  |          0  (omitted)
                                              Aragone J.C.  |          0  (omitted)
                                                Aragone JC  |          0  (omitted)
                                                Arevalo M.  |          0  (omitted)
                                               Arguello F.  |          0  (omitted)
                                              Arnaboldi A.  |          0  (omitted)
                                  Artunedo Martinavarro A.  |          0  (omitted)
                                              Arvidsson I.  |          0  (omitted)
                                        Auger-Aliassime F.  |          0  (omitted)
                                                 Authom M.  |          0  (omitted)
                                                Avidzba A.  |          0  (omitted)
                                              Bachinger M.  |          0  (omitted)
                                                   Baez S.  |          0  (omitted)
                                              Baghdatis M.  |          0  (omitted)
                                                 Bagnis F.  |          0  (omitted)
                                                    Bai Y.  |          0  (omitted)
                                                  Baker B.  |          0  (omitted)
                                                  Baker J.  |          0  (omitted)
                                                 Balazs A.  |          0  (omitted)
                                                  Baldi F.  |          0  (omitted)
                                               Balleret B.  |          0  (omitted)
                                                 Baluda V.  |          0  (omitted)
                                                Barrere G.  |          0  (omitted)
                                                Barrios M.  |          0  (omitted)
                                         Barrios Vera M.T.  |          0  (omitted)
                                                 Barton M.  |          0  (omitted)
                                                  Basic M.  |          0  (omitted)
                                           Basilashvili N.  |          0  (omitted)
                                                  Basso A.  |          0  (omitted)
                                          Bautista Agut R.  |          0  (omitted)
                                               Bautista R.  |          0  (omitted)
                                                   Beck A.  |          0  (omitted)
                                                 Becker B.  |          0  (omitted)
                                                 Bedene A.  |          0  (omitted)
                                                Bellier A.  |          0  (omitted)
                                               Bellucci T.  |          0  (omitted)
                                              Bemelmans R.  |          0  (omitted)
                                             Benchetrit E.  |          0  (omitted)
                                              Benneteau J.  |          0  (omitted)
                                               Berankis R.  |          0  (omitted)
                                                Berdych T.  |          0  (omitted)
                                                  Bergs Z.  |          0  (omitted)
                                                Berlocq C.  |          0  (omitted)
                                                 Berrer M.  |          0  (omitted)
                                             Berrettini M.  |          0  (omitted)
                                                 Bester P.  |          0  (omitted)
                                                Bhambri Y.  |          0  (omitted)
                                               Biryukov M.  |          0  (omitted)
                                                  Blake J.  |          0  (omitted)
                                            Blancaneaux G.  |          0  (omitted)
                                                 Blanch U.  |          0  (omitted)
                                               Bogaerts R.  |          0  (omitted)
                                              Bogomolov A.  |          0  (omitted)
                                                Bolelli S.  |          0  (omitted)
                                                   Bolt A.  |          0  (omitted)
                                                  Bonzi B.  |          0  (omitted)
                                                 Borges N.  |          0  (omitted)
                                                 Bossel A.  |          0  (omitted)
                                              Bourchier H.  |          0  (omitted)
                                                Bourgue M.  |          0  (omitted)
                                               Bozoljac I.  |          0  (omitted)
                                             Brancaccio R.  |          0  (omitted)
                                                 Brands D.  |          0  (omitted)
                                                 Broady L.  |          0  (omitted)
                                               Brooksby J.  |          0  (omitted)
                                                  Brown D.  |          0  (omitted)
                                           Brugues-Davi A.  |          0  (omitted)
                                                  Bryde T.  |          0  (omitted)
                                                 Bublik A.  |          0  (omitted)
                                               Buchanan C.  |          0  (omitted)
                                                 Cachin P.  |          0  (omitted)
                                                  Cacic N.  |          0  (omitted)
                                        Carballes Baena R.  |          0  (omitted)
                                          Carreno Busta P.  |          0  (omitted)
                                          Carreno-Busta P.  |          0  (omitted)
                                                Caruana L.  |          0  (omitted)
                                                 Caruso S.  |          0  (omitted)
                                               Catarina L.  |          0  (omitted)
                                                 Cazaux A.  |          0  (omitted)
                                             Cecchinato M.  |          0  (omitted)
                                             Celikbilek A.  |          0  (omitted)
                                              Cerundolo F.  |          0  (omitted)
                                            Cerundolo J.M.  |          0  (omitted)
                                              Cervantes I.  |          0  (omitted)
                                                 Chardy J.  |          0  (omitted)
                                            Chiudinelli M.  |          0  (omitted)
                                               Choinski J.  |          0  (omitted)
                                             Chrysochos P.  |          0  (omitted)
                                                  Chung H.  |          0  (omitted)
                                                  Cilic M.  |          0  (omitted)
                                                Cipolla F.  |          0  (omitted)
                                                 Clarke J.  |          0  (omitted)
                                                 Clezar G.  |          0  (omitted)
                                                Cobolli F.  |          0  (omitted)
                                              Collarini A.  |          0  (omitted)
                                                  Copil M.  |          0  (omitted)
                                              Coppejans K.  |          0  (omitted)
                                                  Coria F.  |          0  (omitted)
                                                  Coric B.  |          0  (omitted)
                                                 Corrie E.  |          0  (omitted)
                                               Couacaud E.  |          0  (omitted)
                                                    Cox D.  |          0  (omitted)
                                                 Cressy M.  |          0  (omitted)
                                                 Crivoi V.  |          0  (omitted)
                                                 Cuevas P.  |          0  (omitted)
                                               Dancevic F.  |          0  (omitted)
                                                 Daniel T.  |          0  (omitted)
                                                 Darcis S.  |          0  (omitted)
                                      Davidovich Fokina A.  |          0  (omitted)
                                              Davydenko N.  |          0  (omitted)
                                              Davydenko P.  |          0  (omitted)
                                              De Bakker T.  |          0  (omitted)
                                               De Greef A.  |          0  (omitted)
                                               De Loore J.  |          0  (omitted)
                                              De Minaur A.  |          0  (omitted)
                                               De Paula F.  |          0  (omitted)
                                            De Schepper K.  |          0  (omitted)
                                           Del Potro J. M.  |          0  (omitted)
                                            Del Potro J.M.  |          0  (omitted)
                                               Delbonis F.  |          0  (omitted)
                                                  Delic M.  |          0  (omitted)
                                                Dellien H.  |          0  (omitted)
                                                 Desein N.  |          0  (omitted)
                                              Devvarman S.  |          0  (omitted)
                                            Diaz Acosta F.  |          0  (omitted)
                                                   Diez S.  |          0  (omitted)
                                               Dimitrov G.  |          0  (omitted)
                                                  Djere L.  |          0  (omitted)
                                               Djokovic N.  |          0  (omitted)
                                                  Dodig I.  |          0  (omitted)
                                             Dolgopolov A.  |          0  (omitted)
                                             Dolgopolov O.  |          0  (omitted)
                                              Domingues J.  |          0  (omitted)
                                              Donaldson J.  |          0  (omitted)
                                                 Donati M.  |          0  (omitted)
                                                 Donski A.  |          0  (omitted)
                                                Donskoy E.  |          0  (omitted)
                                                 Draper J.  |          0  (omitted)
                                              Dubrivnyy A.  |          0  (omitted)
                                              Duckworth J.  |          0  (omitted)
                                                 Dustov F.  |          0  (omitted)
                                            Dutra Silva R.  |          0  (omitted)
                                                Dzumhur D.  |          0  (omitted)
                                                  Ebden M.  |          0  (omitted)
                                                 Edmund K.  |          0  (omitted)
                                                  Ehrat S.  |          0  (omitted)
                                              El Amrani R.  |          0  (omitted)
                                                  Elgin M.  |          0  (omitted)
                                                  Elias G.  |          0  (omitted)
                                               Eriksson M.  |          0  (omitted)
                                                  Erler A.  |          0  (omitted)
                                               Escobedo E.  |          0  (omitted)
                                        Estrella Burgos V.  |          0  (omitted)
                                             Etcheverry T.  |          0  (omitted)
                                                Eubanks C.  |          0  (omitted)
                                                  Evans D.  |          0  (omitted)
                                               Eysseric J.  |          0  (omitted)
                                               Fabbiano T.  |          0  (omitted)
                                                  Falla A.  |          0  (omitted)
                                                Fancutt T.  |          0  (omitted)
                                                Federer R.  |          0  (omitted)
                                         Ferreira Silva F.  |          0  (omitted)
                                                            |
                                                 tournament |
                                       AEGON Championships  |   .9221968   .2693283     3.42   0.001     .3933429    1.451051
                                       AEGON International  |    .429306   .5291842     0.81   0.418    -.6098019    1.468414
                                               ASB Classic  |   .3400479   .2667856     1.27   0.203    -.1838133    .8639091
                                   ATP Vegeta Croatia Open  |   .0135294   .3922401     0.03   0.972    -.7566747    .7837334
                                          Abierto Mexicano  |  -.2676215    .243872    -1.10   0.273    -.7464895    .2112465
                                    Abierto Mexicano Mifel  |   .1770714   .2908136     0.61   0.543    -.3939712    .7481141
                                              Antalya Open  |   1.122988   .3334145     3.37   0.001     .4682938    1.777682
                                 AnyTech365 Andalucia Open  |   .9905104   .6792252     1.46   0.145    -.3432186    2.324239
                                        Apia International  |   .0028285   .3135462     0.01   0.993    -.6128519    .6185088
                                            Argentina Open  |   .4748834   .2608584     1.82   0.069     -.037339    .9871058
                                               Astana Open  |   1.093702   .4127409     2.65   0.008     .2832425    1.904161
                                           Australian Open  |   6.771053   .2053073    32.98   0.000     6.367911    7.174195
                                         BB&T Atlanta Open  |   .9445622   .2555123     3.70   0.000     .4428373    1.446287
                                                  BMW Open  |   .3512272   .2573884     1.36   0.173    -.1541815    .8566359
                                       BNP Paribas Masters  |   -.115716   .2198033    -0.53   0.599    -.5473225    .3158905
                                          BNP Paribas Open  |   .0570747   .1989617     0.29   0.774    -.3336073    .4477567
                                            Barcelona Open  |   .0324677    .379197     0.09   0.932    -.7121249    .7770602
                                             Belgrade Open  |  -.4813504   .6413672    -0.75   0.453    -1.740741    .7780405
                                           Bet-At-Home Cup  |   .3048193   .4345015     0.70   0.483    -.5483693    1.158008
                                    Brisbane International  |   .4539476    .259291     1.75   0.080    -.0551971    .9630923
                                             Canadian Open  |   -.011328   .3920138    -0.03   0.977    -.7810876    .7584317
                                                Chile Open  |    1.29321    .476949     2.71   0.007     .3566709    2.229748
                                                Copa Claro  |   .1591191   .2702482     0.59   0.556    -.3715412    .6897793
                                              Cordoba Open  |   .7706956   .3599728     2.14   0.033     .0638518    1.477539
                                              Croatia Open  |   .8520246   .2959456     2.88   0.004     .2709048    1.433144
                        Crédit Agricole Suisse Open Gstaad  |    .760332   .4337809     1.75   0.080    -.0914418    1.612106
                                         Delray Beach Open  |  -.0272217   .2561458    -0.11   0.915    -.5301906    .4757471
                                Dubai Tennis Championships  |  -.2093341   .2204723    -0.95   0.343    -.6422542     .223586
                                  Eastbourne International  |   .1996617   .4888344     0.41   0.683    -.7602152    1.159539
                                       Emilia-Romagna Open  |   .1681922    .461026     0.36   0.715      -.73708    1.073464
                                           Erste Bank Open  |   .5173811   .2582161     2.00   0.046     .0103471    1.024415
                                             European Open  |    .536834   .2995517     1.79   0.074    -.0513667    1.125035
                               Forte Village Sardegna Open  |   .4415737   .6073389     0.73   0.467     -.750999    1.634146
                                               French Open  |   6.052136   .2055734    29.44   0.000     5.648472    6.455801
                                   Garanti Koza Sofia Open  |   .5851324   .3244356     1.80   0.072    -.0519304    1.222195
                                    Gazprom Hungarian Open  |    .512104   .4354918     1.18   0.240    -.3430292    1.367237
                                             Generali Open  |   .9817791   .2548783     3.85   0.000     .4812992    1.482259
                                               Geneva Open  |   .6340323   .2886155     2.20   0.028     .0673059    1.200759
                          German Open Tennis Championships  |   .7408355   .4436236     1.67   0.095    -.1302653    1.611936
                               German Tennis Championships  |   .6761851   .2927848     2.31   0.021     .1012718    1.251098
                                          Gerry Weber Open  |  -.0390653     .28527    -0.14   0.891    -.5992225    .5210918
                                      Grand Prix Hassan II  |   .1665062    .252291     0.66   0.510    -.3288933    .6619056
                                     Great Ocean Road Open  |   1.286981   .4405683     2.92   0.004     .4218796    2.152082
                                Hall of Fame Championships  |   .8849701   .2654607     3.33   0.001     .3637104     1.40623
                                                Halle Open  |   .5157782   .3757882     1.37   0.170    -.2221208    1.253677
                                             Heineken Open  |   .7388809   .3246516     2.28   0.023     .1013938    1.376368
                                            Hungarian Open  |   .5062525   .5318353     0.95   0.342    -.5380612    1.550566
                               International Championships  |    .322639   .5141927     0.63   0.531    -.6870315     1.33231
                               Internazionali BNL d'Italia  |   -.393738   .2047279    -1.92   0.055    -.7957424    .0082664
                                       Konzum Croatia Open  |  -.2073697    .448157    -0.46   0.644    -1.087372    .6726331
                                               Kremlin Cup  |   .5263487   .2376689     2.21   0.027     .0596613    .9930362
                                                 Lyon Open  |    .662792   .3143117     2.11   0.035     .0456085    1.279975
                                          Maharashtra Open  |     1.6439   .3742219     4.39   0.000     .9090767    2.378724
                                    Mallorca Championships  |  -.2049577   .4489509    -0.46   0.648    -1.086519    .6766038
                                              Mercedes Cup  |   .7574568   .2533927     2.99   0.003     .2598939     1.25502
                                                Miami Open  |    .320532   .3068321     1.04   0.297    -.2819646    .9230286
                                                Mifel Open  |   .2057915    .517344     0.40   0.691     -.810067     1.22165
                                    Millenium Estoril Open  |   .0166498   .3515993     0.05   0.962    -.6737519    .7070514
                                   Millennium Estoril Open  |     .42329   .3901124     1.09   0.278    -.3427361    1.189316
                                       Monte Carlo Masters  |  -.6109264     .20035    -3.05   0.002    -1.004334   -.2175184
                                         Murray River Open  |    .533906   .4126843     1.29   0.196    -.2764423    1.344254
                                         Mutua Madrid Open  |   .1554741   .2101294     0.74   0.460    -.2571366    .5680849
                                             New York Open  |   1.784026    .350998     5.08   0.000     1.094805    2.473247
                                               Nordea Open  |  -.3198578   .5325536    -0.60   0.548    -1.365582    .7258663
                                                   Open 13  |   .3980304   .2364775     1.68   0.093    -.0663176    .8623785
                                       Open Banco Sabadell  |  -.0398676   .2431644    -0.16   0.870     -.517346    .4376108
                                      Open Banco Sabadell   |  -.3559546   .2964751    -1.20   0.230    -.9381142     .226205
                                        Open Sud de France  |   .6848377    .242777     2.82   0.005     .2081199    1.161555
                                           Open de Moselle  |   .6304402   .2459145     2.56   0.011     .1475616    1.113319
                                    Qatar Exxon Mobil Open  |   .1163426   .2560651     0.45   0.650    -.3864678     .619153
                                Queen's Club Championships  |   .8349375   .4303584     1.94   0.053    -.0101158    1.679991
                                                  Rio Open  |    .456671   .2840875     1.61   0.108    -.1011643    1.014506
                                            Rogers Masters  |   .1768775   .2088813     0.85   0.397    -.2332824    .5870375
                                            San Diego Open  |  -.3994378   .3777248    -1.06   0.291     -1.14114    .3422639
                                             Sardegna Open  |   1.280477   .5503176     2.33   0.020     .1998715    2.361083
                                               Serbia Open  |   .8545094   .5307683     1.61   0.108     -.187709    1.896728
                                          Shanghai Masters  |   .0030055   .2058166     0.01   0.988    -.4011366    .4071476
                                            Singapore Open  |   1.048475   .5390534     1.95   0.052    -.0100126    2.106962
                                      SkiStar Swedish Open  |   .0659715   .2796311     0.24   0.814     -.483113    .6150561
                                                Sofia Open  |    .168902   .4013475     0.42   0.674    -.6191854    .9569893
                                        Sony Ericsson Open  |   .1378258   .1968904     0.70   0.484    -.2487889    .5244406
                                       St. Petersburg Open  |   .5271275   .2159507     2.44   0.015     .1030859    .9511691
                                        Suisse Open Gstaad  |   1.020889   .2982293     3.42   0.001     .4352847    1.606493
                                             Swiss Indoors  |  -.1160826   .2449933    -0.47   0.636    -.5971523    .3649871
                                      Sydney International  |   .6409679   .3871724     1.66   0.098    -.1192853    1.401221
                                                 Tata Open  |    1.38529   .5578909     2.48   0.013     .2898129    2.480766
                       U.S. Men's Clay Court Championships  |   .4167218   .2781995     1.50   0.135    -.1295517    .9629953
                                                   US Open  |   6.514836   .1983645    32.84   0.000     6.125327    6.904345
                                      Viking International  |   .3364844   .6008971     0.56   0.576    -.8434392    1.516408
                Western & Southern Financial Group Masters  |   .1057157   .1920804     0.55   0.582     -.271454    .4828854
                                                 Wimbledon  |   7.103967    .217924    32.60   0.000     6.676051    7.531883
              Winston-Salem Open at Wake Forest University  |   .2773338   .2102498     1.32   0.188    -.1355134     .690181
                                          bet-at-home Open  |   -.485685   .3945315    -1.23   0.219    -1.260388    .2890183
                                   bett1HULKS Championship  |  -.2530199   .6108815    -0.41   0.679    -1.452549    .9465092
                                        bett1HULKS Indoors  |   .1835926   .4879815     0.38   0.707    -.7746096    1.141795
                                                            |
                                                       Year |
                                                      2014  |  -.0581542   .1072969    -0.54   0.588    -.2688427    .1525343
                                                      2015  |   .0179388    .106623     0.17   0.866    -.1914265     .227304
                                                      2016  |  -.1004927   .1202805    -0.84   0.404    -.3366759    .1356905
                                                      2017  |  -.1126795   .1201517    -0.94   0.349    -.3486097    .1232507
                                                      2018  |   .0005407   .1233799     0.00   0.997    -.2417285    .2428099
                                                      2019  |  -.1488783   .1278589    -1.16   0.245    -.3999425    .1021859
                                                      2020  |  -.0632159   .1450582    -0.44   0.663    -.3480527     .221621
                                                      2021  |  -.3199543   .1490957    -2.15   0.032    -.6127192   -.0271895
                                                            |
                                                      _cons |   10.80694   .2103218    51.38   0.000     10.39395    11.21993
              ----------------------------------------------+----------------------------------------------------------------
                                                    sigma_u |  2.5799329
                                                    sigma_e |  4.5959711
                                                        rho |  .23960735   (fraction of variance due to u_i)
              ---------------------------------------------------------------------------------------------------------------

              Comment


              • #8
                Luca:
                your -xtreg,fe- code is wrong.
                It should be:
                Code:
                 
                 . xtreg GameswonbyIndividualPlayer IndividualHeterogeneity IndividualPrizeSpread1000 NumOfTourneys SpreadNumOfTourneys i.tournament i.Year, fe vce(cluster individualplayer)
                as -individualplayer- predictor is clerly collinear with -xtset- panelid.
                Code:
                note: 2.individualplayer omitted because of collinearity.
                As an aside, I think you should take a look at any decent textbook on panel data econometrics and get yourself familiar with the building blocks of this stuff, which is not trivial at all (see the reference in -xtreg- entry, Stata .pdf manual).
                Kind regards,
                Carlo
                (Stata 18.0 SE)

                Comment


                • #9
                  Originally posted by Carlo Lazzaro View Post
                  Luca:
                  your -xtreg,fe- code is wrong.
                  It should be:
                  Code:
                  . xtreg GameswonbyIndividualPlayer IndividualHeterogeneity IndividualPrizeSpread1000 NumOfTourneys SpreadNumOfTourneys i.tournament i.Year, fe vce(cluster individualplayer)
                  as -individualplayer- predictor is clerly collinear with -xtset- panelid.
                  Code:
                  note: 2.individualplayer omitted because of collinearity.
                  As an aside, I think you should take a look at any decent textbook on panel data econometrics and get yourself familiar with the building blocks of this stuff, which is not trivial at all (see the reference in -xtreg- entry, Stata .pdf manual).
                  Thanks Carlo.
                  1) By defining the xtset to indiviudal player, does it technically mean that we still use player fixed effects or if we drop the i.individual player (due to collinearity) it is no longer a player fixed effect?
                  2) If I want to run this regression https://gyazo.com/994caa3fd252bc7cd084df5e47612c54 only with tournaments fixed effects and year fixed effect, will the code be like that?
                  Code:
                   xtset tournament
                  
                  Panel variable: tournament (unbalanced)
                  
                  . xtreg GameswonbyIndividualPlayer IndividualHeterogeneity IndividualPrizeSpread1000 i.Year, fe vce(cluster tournament) 
                  
                  Fixed-effects (within) regression               Number of obs     =     37,060
                  Group variable: tournament                      Number of groups  =         96
                  
                  R-squared:                                      Obs per group:
                       Within  = 0.0290                                         min =         52
                       Between = 0.0446                                         avg =      386.0
                       Overall = 0.0244                                         max =      2,284
                  
                                                                  F(10,95)          =      15.83
                  corr(u_i, Xb) = 0.0176                          Prob > F          =     0.0000
                  
                                                           (Std. err. adjusted for 96 clusters in tournament)
                  -------------------------------------------------------------------------------------------
                                            |               Robust
                  GameswonbyIndividualPla~r | Coefficient  std. err.      t    P>|t|     [95% conf. interval]
                  --------------------------+----------------------------------------------------------------
                    IndividualHeterogeneity |  -.0064057   .0007454    -8.59   0.000    -.0078856   -.0049259
                  IndividualPrizeSpread1000 |     .00078   .0005314     1.47   0.145    -.0002749     .001835
                                            |
                                       Year |
                                      2014  |   .0530174   .1634527     0.32   0.746    -.2714772     .377512
                                      2015  |   .2237037   .1410263     1.59   0.116    -.0562689    .5036763
                                      2016  |   .1306217   .1205974     1.08   0.281    -.1087945    .3700379
                                      2017  |   .1782277   .0959549     1.86   0.066    -.0122669    .3687223
                                      2018  |   .3316397   .1436798     2.31   0.023     .0463994    .6168801
                                      2019  |   .2820351   .1010054     2.79   0.006     .0815141    .4825561
                                      2020  |   .2277744   .1285709     1.77   0.080    -.0274711      .48302
                                      2021  |   .1990837   .1701854     1.17   0.245    -.1387771    .5369444
                                            |
                                      _cons |   12.78785   .0980222   130.46   0.000     12.59326    12.98245
                  --------------------------+----------------------------------------------------------------
                                    sigma_u |  1.3376777
                                    sigma_e |  4.6590817
                                        rho |  .07615549   (fraction of variance due to u_i)
                  -------------------------------------------------------------------------------------

                  Comment


                  • #10
                    Luca:
                    1) By defining the xtset to indiviudal player, it technically means that you are investigating player fixed effects.
                    2) Correct. But looking at -sigmas-, you probably do not have a panel-wise effect (the within R-sq is also really low). This might be due to a poor specified model or a real absence of panel-wise effect in your data.
                    Kind regards,
                    Carlo
                    (Stata 18.0 SE)

                    Comment


                    • #11
                      Originally posted by Carlo Lazzaro View Post
                      Luca:
                      1) By defining the xtset to indiviudal player, it technically means that you are investigating player fixed effects.
                      2) Correct. But looking at -sigmas-, you probably do not have a panel-wise effect (the within R-sq is also really low). This might be due to a poor specified model or a real absence of panel-wise effect in your data.
                      You're right. It's indeed very low. I will see what can I do to specify the model better. At least now I feel much better about the whole process so thanks a lot.
                      Another question - how can I present the results like in this table, for example https://gyazo.com/417a70a8863a22f0249788562de94c6a? I mean from the "tournament dummies" until "R-sq" rows. Basically I know I should use eststo command to store each regression, then I should use esttab to print the regressions on table, but how can I present it in the same way like in the picture. If I use eststo and esttab for the three regressions, this is what I get and it looks horrible...
                      Code:
                      . encode Tournament, g(tournament)
                      
                      . encode Nationality, g(nationality)
                      
                      . encode IndividualPlayer, g(individualplayer)
                      
                      . xtset individualplayer
                      
                      Panel variable: individualplayer (unbalanced)
                      
                      . eststo: xtreg GameswonbyIndividualPlayer IndividualHeterogeneity IndividualPrizeSpread1000 NumOfTourneys SpreadNumOfTourneys i.tournament i.Year, fe vce(cluster individualplayer)
                      
                      Fixed-effects (within) regression               Number of obs     =     37,060
                      Group variable: individual~r                    Number of groups  =        654
                      
                      R-squared:                                      Obs per group:
                           Within  = 0.2642                                         min =          1
                           Between = 0.3731                                         avg =       56.7
                           Overall = 0.2701                                         max =        509
                      
                                                                      F(107,653)        =     122.84
                      corr(u_i, Xb) = 0.0431                          Prob > F          =     0.0000
                      
                                                                            (Std. err. adjusted for 654 clusters in individualplayer)
                      ---------------------------------------------------------------------------------------------------------------
                                                                    |               Robust
                                         GameswonbyIndividualPlayer | Coefficient  std. err.      t    P>|t|     [95% conf. interval]
                      ----------------------------------------------+----------------------------------------------------------------
                                            IndividualHeterogeneity |  -.0049322   .0003348   -14.73   0.000    -.0055897   -.0042748
                                          IndividualPrizeSpread1000 |    .003734   .0015154     2.46   0.014     .0007583    .0067097
                                                      NumOfTourneys |   .0344991   .0070374     4.90   0.000     .0206803    .0483178
                                                SpreadNumOfTourneys |  -.0003388     .00011    -3.08   0.002    -.0005547   -.0001228
                                                                    |
                                                         tournament |
                                               AEGON Championships  |   .9221968   .2693283     3.42   0.001     .3933429    1.451051
                                               AEGON International  |    .429306   .5291842     0.81   0.418    -.6098019    1.468414
                                                       ASB Classic  |   .3400479   .2667856     1.27   0.203    -.1838133    .8639091
                                           ATP Vegeta Croatia Open  |   .0135294   .3922401     0.03   0.972    -.7566747    .7837334
                                                  Abierto Mexicano  |  -.2676215    .243872    -1.10   0.273    -.7464895    .2112465
                                            Abierto Mexicano Mifel  |   .1770714   .2908136     0.61   0.543    -.3939712    .7481141
                                                      Antalya Open  |   1.122988   .3334145     3.37   0.001     .4682938    1.777682
                                         AnyTech365 Andalucia Open  |   .9905104   .6792252     1.46   0.145    -.3432186    2.324239
                                                Apia International  |   .0028285   .3135462     0.01   0.993    -.6128519    .6185088
                                                    Argentina Open  |   .4748834   .2608584     1.82   0.069     -.037339    .9871058
                                                       Astana Open  |   1.093702   .4127409     2.65   0.008     .2832425    1.904161
                                                   Australian Open  |   6.771053   .2053073    32.98   0.000     6.367911    7.174195
                                                 BB&T Atlanta Open  |   .9445622   .2555123     3.70   0.000     .4428373    1.446287
                                                          BMW Open  |   .3512272   .2573884     1.36   0.173    -.1541815    .8566359
                                               BNP Paribas Masters  |   -.115716   .2198033    -0.53   0.599    -.5473225    .3158905
                                                  BNP Paribas Open  |   .0570747   .1989617     0.29   0.774    -.3336073    .4477567
                                                    Barcelona Open  |   .0324677    .379197     0.09   0.932    -.7121249    .7770602
                                                     Belgrade Open  |  -.4813504   .6413672    -0.75   0.453    -1.740741    .7780405
                                                   Bet-At-Home Cup  |   .3048193   .4345015     0.70   0.483    -.5483693    1.158008
                                            Brisbane International  |   .4539476    .259291     1.75   0.080    -.0551971    .9630923
                                                     Canadian Open  |   -.011328   .3920138    -0.03   0.977    -.7810876    .7584317
                                                        Chile Open  |    1.29321    .476949     2.71   0.007     .3566709    2.229748
                                                        Copa Claro  |   .1591191   .2702482     0.59   0.556    -.3715412    .6897793
                                                      Cordoba Open  |   .7706956   .3599728     2.14   0.033     .0638518    1.477539
                                                      Croatia Open  |   .8520246   .2959456     2.88   0.004     .2709048    1.433144
                                Crédit Agricole Suisse Open Gstaad  |    .760332   .4337809     1.75   0.080    -.0914418    1.612106
                                                 Delray Beach Open  |  -.0272217   .2561458    -0.11   0.915    -.5301906    .4757471
                                        Dubai Tennis Championships  |  -.2093341   .2204723    -0.95   0.343    -.6422542     .223586
                                          Eastbourne International  |   .1996617   .4888344     0.41   0.683    -.7602152    1.159539
                                               Emilia-Romagna Open  |   .1681922    .461026     0.36   0.715      -.73708    1.073464
                                                   Erste Bank Open  |   .5173811   .2582161     2.00   0.046     .0103471    1.024415
                                                     European Open  |    .536834   .2995517     1.79   0.074    -.0513667    1.125035
                                       Forte Village Sardegna Open  |   .4415737   .6073389     0.73   0.467     -.750999    1.634146
                                                       French Open  |   6.052136   .2055734    29.44   0.000     5.648472    6.455801
                                           Garanti Koza Sofia Open  |   .5851324   .3244356     1.80   0.072    -.0519304    1.222195
                                            Gazprom Hungarian Open  |    .512104   .4354918     1.18   0.240    -.3430292    1.367237
                                                     Generali Open  |   .9817791   .2548783     3.85   0.000     .4812992    1.482259
                                                       Geneva Open  |   .6340323   .2886155     2.20   0.028     .0673059    1.200759
                                  German Open Tennis Championships  |   .7408355   .4436236     1.67   0.095    -.1302653    1.611936
                                       German Tennis Championships  |   .6761851   .2927848     2.31   0.021     .1012718    1.251098
                                                  Gerry Weber Open  |  -.0390653     .28527    -0.14   0.891    -.5992225    .5210918
                                              Grand Prix Hassan II  |   .1665062    .252291     0.66   0.510    -.3288933    .6619056
                                             Great Ocean Road Open  |   1.286981   .4405683     2.92   0.004     .4218796    2.152082
                                        Hall of Fame Championships  |   .8849701   .2654607     3.33   0.001     .3637104     1.40623
                                                        Halle Open  |   .5157782   .3757882     1.37   0.170    -.2221208    1.253677
                                                     Heineken Open  |   .7388809   .3246516     2.28   0.023     .1013938    1.376368
                                                    Hungarian Open  |   .5062525   .5318353     0.95   0.342    -.5380612    1.550566
                                       International Championships  |    .322639   .5141927     0.63   0.531    -.6870315     1.33231
                                       Internazionali BNL d'Italia  |   -.393738   .2047279    -1.92   0.055    -.7957424    .0082664
                                               Konzum Croatia Open  |  -.2073697    .448157    -0.46   0.644    -1.087372    .6726331
                                                       Kremlin Cup  |   .5263487   .2376689     2.21   0.027     .0596613    .9930362
                                                         Lyon Open  |    .662792   .3143117     2.11   0.035     .0456085    1.279975
                                                  Maharashtra Open  |     1.6439   .3742219     4.39   0.000     .9090767    2.378724
                                            Mallorca Championships  |  -.2049577   .4489509    -0.46   0.648    -1.086519    .6766038
                                                      Mercedes Cup  |   .7574568   .2533927     2.99   0.003     .2598939     1.25502
                                                        Miami Open  |    .320532   .3068321     1.04   0.297    -.2819646    .9230286
                                                        Mifel Open  |   .2057915    .517344     0.40   0.691     -.810067     1.22165
                                            Millenium Estoril Open  |   .0166498   .3515993     0.05   0.962    -.6737519    .7070514
                                           Millennium Estoril Open  |     .42329   .3901124     1.09   0.278    -.3427361    1.189316
                                               Monte Carlo Masters  |  -.6109264     .20035    -3.05   0.002    -1.004334   -.2175184
                                                 Murray River Open  |    .533906   .4126843     1.29   0.196    -.2764423    1.344254
                                                 Mutua Madrid Open  |   .1554741   .2101294     0.74   0.460    -.2571366    .5680849
                                                     New York Open  |   1.784026    .350998     5.08   0.000     1.094805    2.473247
                                                       Nordea Open  |  -.3198578   .5325536    -0.60   0.548    -1.365582    .7258663
                                                           Open 13  |   .3980304   .2364775     1.68   0.093    -.0663176    .8623785
                                               Open Banco Sabadell  |  -.0398676   .2431644    -0.16   0.870     -.517346    .4376108
                                              Open Banco Sabadell   |  -.3559546   .2964751    -1.20   0.230    -.9381142     .226205
                                                Open Sud de France  |   .6848377    .242777     2.82   0.005     .2081199    1.161555
                                                   Open de Moselle  |   .6304402   .2459145     2.56   0.011     .1475616    1.113319
                                            Qatar Exxon Mobil Open  |   .1163426   .2560651     0.45   0.650    -.3864678     .619153
                                        Queen's Club Championships  |   .8349375   .4303584     1.94   0.053    -.0101158    1.679991
                                                          Rio Open  |    .456671   .2840875     1.61   0.108    -.1011643    1.014506
                                                    Rogers Masters  |   .1768775   .2088813     0.85   0.397    -.2332824    .5870375
                                                    San Diego Open  |  -.3994378   .3777248    -1.06   0.291     -1.14114    .3422639
                                                     Sardegna Open  |   1.280477   .5503176     2.33   0.020     .1998715    2.361083
                                                       Serbia Open  |   .8545094   .5307683     1.61   0.108     -.187709    1.896728
                                                  Shanghai Masters  |   .0030055   .2058166     0.01   0.988    -.4011366    .4071476
                                                    Singapore Open  |   1.048475   .5390534     1.95   0.052    -.0100126    2.106962
                                              SkiStar Swedish Open  |   .0659715   .2796311     0.24   0.814     -.483113    .6150561
                                                        Sofia Open  |    .168902   .4013475     0.42   0.674    -.6191854    .9569893
                                                Sony Ericsson Open  |   .1378258   .1968904     0.70   0.484    -.2487889    .5244406
                                               St. Petersburg Open  |   .5271275   .2159507     2.44   0.015     .1030859    .9511691
                                                Suisse Open Gstaad  |   1.020889   .2982293     3.42   0.001     .4352847    1.606493
                                                     Swiss Indoors  |  -.1160826   .2449933    -0.47   0.636    -.5971523    .3649871
                                              Sydney International  |   .6409679   .3871724     1.66   0.098    -.1192853    1.401221
                                                         Tata Open  |    1.38529   .5578909     2.48   0.013     .2898129    2.480766
                               U.S. Men's Clay Court Championships  |   .4167218   .2781995     1.50   0.135    -.1295517    .9629953
                                                           US Open  |   6.514836   .1983645    32.84   0.000     6.125327    6.904345
                                              Viking International  |   .3364844   .6008971     0.56   0.576    -.8434392    1.516408
                        Western & Southern Financial Group Masters  |   .1057157   .1920804     0.55   0.582     -.271454    .4828854
                                                         Wimbledon  |   7.103967    .217924    32.60   0.000     6.676051    7.531883
                      Winston-Salem Open at Wake Forest University  |   .2773338   .2102498     1.32   0.188    -.1355134     .690181
                                                  bet-at-home Open  |   -.485685   .3945315    -1.23   0.219    -1.260388    .2890183
                                           bett1HULKS Championship  |  -.2530199   .6108815    -0.41   0.679    -1.452549    .9465092
                                                bett1HULKS Indoors  |   .1835926   .4879815     0.38   0.707    -.7746096    1.141795
                                                                    |
                                                               Year |
                                                              2014  |  -.0581542   .1072969    -0.54   0.588    -.2688427    .1525343
                                                              2015  |   .0179388    .106623     0.17   0.866    -.1914265     .227304
                                                              2016  |  -.1004927   .1202805    -0.84   0.404    -.3366759    .1356905
                                                              2017  |  -.1126795   .1201517    -0.94   0.349    -.3486097    .1232507
                                                              2018  |   .0005407   .1233799     0.00   0.997    -.2417285    .2428099
                                                              2019  |  -.1488783   .1278589    -1.16   0.245    -.3999425    .1021859
                                                              2020  |  -.0632159   .1450582    -0.44   0.663    -.3480527     .221621
                                                              2021  |  -.3199543   .1490957    -2.15   0.032    -.6127192   -.0271895
                                                                    |
                                                              _cons |   10.80694   .2103218    51.38   0.000     10.39395    11.21993
                      ----------------------------------------------+----------------------------------------------------------------
                                                            sigma_u |  2.5799329
                                                            sigma_e |  4.5959711
                                                                rho |  .23960735   (fraction of variance due to u_i)
                      ---------------------------------------------------------------------------------------------------------------
                      (est1 stored)
                      
                      . //second regression
                      . xtset tournament
                      
                      Panel variable: tournament (unbalanced)
                      
                      . eststo: xtreg GameswonbyIndividualPlayer IndividualHeterogeneity IndividualPrizeSpread1000 i.Year, fe vce(cluster tournament)
                      
                      Fixed-effects (within) regression               Number of obs     =     37,060
                      Group variable: tournament                      Number of groups  =         96
                      
                      R-squared:                                      Obs per group:
                           Within  = 0.0290                                         min =         52
                           Between = 0.0446                                         avg =      386.0
                           Overall = 0.0244                                         max =      2,284
                      
                                                                      F(10,95)          =      15.83
                      corr(u_i, Xb) = 0.0176                          Prob > F          =     0.0000
                      
                                                               (Std. err. adjusted for 96 clusters in tournament)
                      -------------------------------------------------------------------------------------------
                                                |               Robust
                      GameswonbyIndividualPla~r | Coefficient  std. err.      t    P>|t|     [95% conf. interval]
                      --------------------------+----------------------------------------------------------------
                        IndividualHeterogeneity |  -.0064057   .0007454    -8.59   0.000    -.0078856   -.0049259
                      IndividualPrizeSpread1000 |     .00078   .0005314     1.47   0.145    -.0002749     .001835
                                                |
                                           Year |
                                          2014  |   .0530174   .1634527     0.32   0.746    -.2714772     .377512
                                          2015  |   .2237037   .1410263     1.59   0.116    -.0562689    .5036763
                                          2016  |   .1306217   .1205974     1.08   0.281    -.1087945    .3700379
                                          2017  |   .1782277   .0959549     1.86   0.066    -.0122669    .3687223
                                          2018  |   .3316397   .1436798     2.31   0.023     .0463994    .6168801
                                          2019  |   .2820351   .1010054     2.79   0.006     .0815141    .4825561
                                          2020  |   .2277744   .1285709     1.77   0.080    -.0274711      .48302
                                          2021  |   .1990837   .1701854     1.17   0.245    -.1387771    .5369444
                                                |
                                          _cons |   12.78785   .0980222   130.46   0.000     12.59326    12.98245
                      --------------------------+----------------------------------------------------------------
                                        sigma_u |  1.3376777
                                        sigma_e |  4.6590817
                                            rho |  .07615549   (fraction of variance due to u_i)
                      -------------------------------------------------------------------------------------------
                      (est2 stored)
                      
                      . //third regression
                      . eststo: xtreg Totalsumofgameswonpermatch Heterogeneity PrizeSpread1000 i.Year, fe vce(cluster tournament)
                      
                      Fixed-effects (within) regression               Number of obs     =     18,530
                      Group variable: tournament                      Number of groups  =         96
                      
                      R-squared:                                      Obs per group:
                           Within  = 0.0025                                         min =         26
                           Between = 0.0346                                         avg =      193.0
                           Overall = 0.0047                                         max =      1,142
                      
                                                                      F(10,95)          =       4.11
                      corr(u_i, Xb) = 0.0466                          Prob > F          =     0.0001
                      
                                                     (Std. err. adjusted for 96 clusters in tournament)
                      ---------------------------------------------------------------------------------
                                      |               Robust
                      Totalsumofgam~h | Coefficient  std. err.      t    P>|t|     [95% conf. interval]
                      ----------------+----------------------------------------------------------------
                        Heterogeneity |  -.0029323    .000661    -4.44   0.000    -.0042446   -.0016201
                      PrizeSpread1000 |   .0012838    .001056     1.22   0.227    -.0008127    .0033803
                                      |
                                 Year |
                                2014  |   .1011909    .328261     0.31   0.759    -.5504896    .7528713
                                2015  |   .4427819   .2828212     1.57   0.121    -.1186891    1.004253
                                2016  |   .2877377   .2465436     1.17   0.246    -.2017133    .7771887
                                2017  |   .3870941   .1911552     2.03   0.046      .007603    .7665852
                                2018  |   .6631707   .2890163     2.29   0.024     .0894009    1.236941
                                2019  |   .5373085   .2030384     2.65   0.010     .1342264    .9403906
                                2020  |   .4509775   .2602063     1.73   0.086    -.0655973    .9675523
                                2021  |   .4031422   .3396756     1.19   0.238    -.2711992    1.077484
                                      |
                                _cons |   25.77718   .1931645   133.45   0.000      25.3937    26.16066
                      ----------------+----------------------------------------------------------------
                              sigma_u |  2.6760201
                              sigma_e |  7.5346964
                                  rho |  .11200966   (fraction of variance due to u_i)
                      ---------------------------------------------------------------------------------
                      (est3 stored)
                      
                      . esttab
                      
                      ------------------------------------------------------------
                                            (1)             (2)             (3)  
                                   Gameswon~yer    Gameswon~yer    Totalsumof~h  
                      ------------------------------------------------------------
                      Individual~y     -0.00493***     -0.00641***                
                                       (-14.73)         (-8.59)                  
                      
                      Individ~1000      0.00373*       0.000780                  
                                         (2.46)          (1.47)                  
                      
                      NumOfTourn~s       0.0345***                                
                                         (4.90)                                  
                      
                      SpreadNumO~s    -0.000339**                                
                                        (-3.08)                                  
                      
                      1.tournament            0                                  
                                            (.)                                  
                      
                      2.tournament        0.922***                                
                                         (3.42)                                  
                      
                      3.tournament        0.429                                  
                                         (0.81)                                  
                      
                      4.tournament        0.340                                  
                                         (1.27)                                  
                      
                      5.tournament       0.0135                                  
                                         (0.03)                                  
                      
                      6.tournament       -0.268                                  
                                        (-1.10)                                  
                      
                      7.tournament        0.177                                  
                                         (0.61)                                  
                      
                      8.tournament        1.123***                                
                                         (3.37)                                  
                      
                      9.tournament        0.991                                  
                                         (1.46)                                  
                      
                      10.tournam~t      0.00283                                  
                                         (0.01)                                  
                      
                      11.tournam~t        0.475                                  
                                         (1.82)                                  
                      
                      12.tournam~t        1.094**                                
                                         (2.65)                                  
                      
                      13.tournam~t        6.771***                                
                                        (32.98)                                  
                      
                      14.tournam~t        0.945***                                
                                         (3.70)                                  
                      
                      15.tournam~t        0.351                                  
                                         (1.36)                                  
                      
                      16.tournam~t       -0.116                                  
                                        (-0.53)                                  
                      
                      17.tournam~t       0.0571                                  
                                         (0.29)                                  
                      
                      18.tournam~t       0.0325                                  
                                         (0.09)                                  
                      
                      19.tournam~t       -0.481                                  
                                        (-0.75)                                  
                      
                      20.tournam~t        0.305                                  
                                         (0.70)                                  
                      
                      21.tournam~t        0.454                                  
                                         (1.75)                                  
                      
                      22.tournam~t      -0.0113                                  
                                        (-0.03)                                  
                      
                      23.tournam~t        1.293**                                
                                         (2.71)                                  
                      
                      24.tournam~t        0.159                                  
                                         (0.59)                                  
                      
                      25.tournam~t        0.771*                                  
                                         (2.14)                                  
                      
                      26.tournam~t        0.852**                                
                                         (2.88)                                  
                      
                      27.tournam~t        0.760                                  
                                         (1.75)                                  
                      
                      28.tournam~t      -0.0272                                  
                                        (-0.11)                                  
                      
                      29.tournam~t       -0.209                                  
                                        (-0.95)                                  
                      
                      30.tournam~t        0.200                                  
                                         (0.41)                                  
                      
                      31.tournam~t        0.168                                  
                                         (0.36)                                  
                      
                      32.tournam~t        0.517*                                  
                                         (2.00)                                  
                      
                      33.tournam~t        0.537                                  
                                         (1.79)                                  
                      
                      34.tournam~t        0.442                                  
                                         (0.73)                                  
                      
                      35.tournam~t        6.052***                                
                                        (29.44)                                  
                      
                      36.tournam~t        0.585                                  
                                         (1.80)                                  
                      
                      37.tournam~t        0.512                                  
                                         (1.18)                                  
                      
                      38.tournam~t        0.982***                                
                                         (3.85)                                  
                      
                      39.tournam~t        0.634*                                  
                                         (2.20)                                  
                      
                      40.tournam~t        0.741                                  
                                         (1.67)                                  
                      
                      41.tournam~t        0.676*                                  
                                         (2.31)                                  
                      
                      42.tournam~t      -0.0391                                  
                                        (-0.14)                                  
                      
                      43.tournam~t        0.167                                  
                                         (0.66)                                  
                      
                      44.tournam~t        1.287**                                
                                         (2.92)                                  
                      
                      45.tournam~t        0.885***                                
                                         (3.33)                                  
                      
                      46.tournam~t        0.516                                  
                                         (1.37)                                  
                      
                      47.tournam~t        0.739*                                  
                                         (2.28)                                  
                      
                      48.tournam~t        0.506                                  
                                         (0.95)                                  
                      
                      49.tournam~t        0.323                                  
                                         (0.63)                                  
                      
                      50.tournam~t       -0.394                                  
                                        (-1.92)                                  
                      
                      51.tournam~t       -0.207                                  
                                        (-0.46)                                  
                      
                      52.tournam~t        0.526*                                  
                                         (2.21)                                  
                      
                      53.tournam~t        0.663*                                  
                                         (2.11)                                  
                      
                      54.tournam~t        1.644***                                
                                         (4.39)                                  
                      
                      55.tournam~t       -0.205                                  
                                        (-0.46)                                  
                      
                      56.tournam~t        0.757**                                
                                         (2.99)                                  
                      
                      57.tournam~t        0.321                                  
                                         (1.04)                                  
                      
                      58.tournam~t        0.206                                  
                                         (0.40)                                                                                  
                      .
                      .
                      .            
                      96.tournam~t        0.184                                  
                                         (0.38)                                  
                      
                      2013.Year               0               0               0  
                                            (.)             (.)             (.)  
                      
                      2014.Year         -0.0582          0.0530           0.101  
                                        (-0.54)          (0.32)          (0.31)  
                      
                      2015.Year          0.0179           0.224           0.443  
                                         (0.17)          (1.59)          (1.57)  
                      
                      2016.Year          -0.100           0.131           0.288  
                                        (-0.84)          (1.08)          (1.17)  
                      
                      2017.Year          -0.113           0.178           0.387*  
                                        (-0.94)          (1.86)          (2.03)  
                      
                      2018.Year        0.000541           0.332*          0.663*  
                                         (0.00)          (2.31)          (2.29)  
                      
                      2019.Year          -0.149           0.282**         0.537**
                                        (-1.16)          (2.79)          (2.65)  
                      
                      2020.Year         -0.0632           0.228           0.451  
                                        (-0.44)          (1.77)          (1.73)  
                      
                      2021.Year          -0.320*          0.199           0.403  
                                        (-2.15)          (1.17)          (1.19)  
                      
                      Heterogene~y                                     -0.00293***
                                                                        (-4.44)  
                      
                      PrizeSp~1000                                      0.00128  
                                                                         (1.22)  
                      
                      _cons               10.81***        12.79***        25.78***
                                        (51.38)        (130.46)        (133.45)  
                      ------------------------------------------------------------
                      N                   37060           37060           18530  
                      ------------------------------------------------------------
                      t statistics in parentheses
                      * p<0.05, ** p<0.01, *** p<0.001

                      Comment


                      • #12
                        Luca:
                        1) if you are working with Stata 17, the totally revised -table- suite can help you out in this respect;
                        2) instead of including the tournaments the way you did, couldn't you group them together according to ATP points (and create a categorical predictor with as many levels as the point categories; 250....1000)?
                        Kind regards,
                        Carlo
                        (Stata 18.0 SE)

                        Comment


                        • #13
                          Originally posted by Carlo Lazzaro View Post
                          Luca:
                          1) if you are working with Stata 17, the totally revised -table- suite can help you out in this respect;
                          2) instead of including the tournaments the way you did, couldn't you group them together according to ATP points (and create a categorical predictor with as many levels as the point categories; 250....1000)?
                          1) Thanks, I'll take a look.
                          2) I don't think I understood you. Could you give me an example?

                          Comment


                          • #14
                            Luca:
                            2) I meant to calculate the effect of the following predictor -i.ATP_points- (0=250 points a tournament; 1=500 points a tournament; 2=1000 points a tournament).
                            In my former tennis player's opinion, does not make sense to include in the same category (I mean -i.tournament-) the Rio Open (250 points) and Wimbledon.
                            Kind regards,
                            Carlo
                            (Stata 18.0 SE)

                            Comment


                            • #15
                              Originally posted by Carlo Lazzaro View Post
                              Luca:
                              2) I meant to calculate the effect of the following predictor -i.ATP_points- (0=250 points a tournament; 1=500 points a tournament; 2=1000 points a tournament).
                              In my former tennis player's opinion, does not make sense to include in the same category (I mean -i.tournament-) the Rio Open (250 points) and Wimbledon.
                              Absolutely. You mean for the Series variable which includes Grand Slam, Masters, ATP 250, ATP 500. I think it could yield better results when we check it for each group separately so I agree with you. Problem is that I don't know the commands to make it so I'm going to need your help.

                              Comment

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