Panel data sample distribution

[jaskaran kaur]

Hello Everyone,

I am looking for a STATA command which can give sample distribution by year and how many firms I have for each year. Below is the example:

Year Number of observations Percent Number of unique firm Percent
2004 870 7.56 870 57.73
2005 890 7.73 89 5.91
2006 941 8.18 110 7.30

I have tried tab1 year, but it only gives me number of observations for each year not the number firms for each year.


Thank you in advance.

Regards
Jaskaran Kaur

[Carlo Lazzaro]

Jaskaran:
Maybe the folowing toy-example will be helpful:

. use "http://www.stata-press.com/data/r15/nlswork.dta"

. bysort year: egen flag=count(idcode)

. tab flag

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1232 |      1,232        4.32        4.32
       1375 |      1,375        4.82        9.14
       1686 |      1,686        5.91       15.05
       1693 |      1,693        5.93       20.98
       1847 |      1,847        6.47       27.45
       1851 |      1,851        6.49       33.94
       1964 |      1,964        6.88       40.82
       1981 |      1,981        6.94       47.76
       1987 |      1,987        6.96       54.73
       2085 |      4,170       14.61       69.34
       2141 |      2,141        7.50       76.85
       2164 |      2,164        7.58       84.43
       2171 |      2,171        7.61       92.04
       2272 |      2,272        7.96      100.00
------------+-----------------------------------
      Total |     28,534      100.00


. bysort year: tab  flag

--------------------------------------------------------------------------------------------------------------------
-> year = 68

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1375 |      1,375      100.00      100.00
------------+-----------------------------------
      Total |      1,375      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 69

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1232 |      1,232      100.00      100.00
------------+-----------------------------------
      Total |      1,232      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 70

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1686 |      1,686      100.00      100.00
------------+-----------------------------------
      Total |      1,686      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 71

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1851 |      1,851      100.00      100.00
------------+-----------------------------------
      Total |      1,851      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 72

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1693 |      1,693      100.00      100.00
------------+-----------------------------------
      Total |      1,693      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 73

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1981 |      1,981      100.00      100.00
------------+-----------------------------------
      Total |      1,981      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 75

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       2141 |      2,141      100.00      100.00
------------+-----------------------------------
      Total |      2,141      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 77

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       2171 |      2,171      100.00      100.00
------------+-----------------------------------
      Total |      2,171      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 78

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1964 |      1,964      100.00      100.00
------------+-----------------------------------
      Total |      1,964      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 80

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1847 |      1,847      100.00      100.00
------------+-----------------------------------
      Total |      1,847      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 82

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       2085 |      2,085      100.00      100.00
------------+-----------------------------------
      Total |      2,085      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 83

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       1987 |      1,987      100.00      100.00
------------+-----------------------------------
      Total |      1,987      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 85

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       2085 |      2,085      100.00      100.00
------------+-----------------------------------
      Total |      2,085      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 87

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       2164 |      2,164      100.00      100.00
------------+-----------------------------------
      Total |      2,164      100.00

--------------------------------------------------------------------------------------------------------------------
-> year = 88

       flag |      Freq.     Percent        Cum.
------------+-----------------------------------
       2272 |      2,272      100.00      100.00
------------+-----------------------------------
      Total |      2,272      100.00


.

.