xi regression variables

[Bannin William]

Good evening,

I've run xi:reg. with interaction effects between a dummy variable (Aft_Cov) and a string variable (Subject) to see its effects on GD (my y variable). The command I ran is xi:reg GD i.Bef_Cov*i.Subject.

There are approximately 150 subjects and in my output it has both Subject == BIOMD with a coefficient as well as Subject == BIOMD ==0 with no coefficient.

I'm concerned whether this has an impact on my results and if it impacts my results, if there is a way to avoid this from occurring.

Cheers,
Bannin

[Carlo Lazzaro]

Bannin:
welcome to this forum.
Three comments about your post:
1) the -xi- prefix is redundant with -regress-; see -fvvarlist- notation instead;
2) I'm not clear with your code. How could a -string- variable be part of an interaction?;
3) please see the FAQ on how to post more effectively, sharing, at minimum, what you typed and what Stata gave you back via CODE delimiters. Thanks.

[Bannin William]

Sorry for my poorly worded post and thank you for the welcome Carlo,

Regarding your first comment, I will make use of the -fvvarlist- notation instead, thank you.
For your second comment. The -string- variable Subject is part of the interaction as I wish to examine the interaction effect between the Bef_Cov and different Subjects (one of them being BIOMD).
My issue is that in my excel output it has given me for example both Subject == BIOMD with a coefficient as well as Subject == BIOMD == 0 with no coefficient.
I'm wondering if it is due to them being omitted due to collinearity or if it has an impact on my results and I should use a different command.

My code is as follows.

xi:reg GD i.Bef_Cov*i.Subject, robust
outreg2 using WIL_reg, replace label excel

This gave the output

i.Bef_Cov         _IBef_Cov_0-1       (naturally coded; _IBef_Cov_0 omitted)
i.Subject         _ISubject_1-152     (_ISubject_1 for Subject==ACCTN omitted)
i.Bef~v*i.Sub~t   _IBefXSub_#_#       (coded as above)
note: _IBefXSub_1_3 omitted because of collinearity
note: _IBefXSub_1_6 omitted because of collinearity
note: _IBefXSub_1_8 omitted because of collinearity
note: _IBefXSub_1_10 omitted because of collinearity
note: _IBefXSub_1_12 omitted because of collinearity
note: _IBefXSub_1_14 omitted because of collinearity
note: _IBefXSub_1_17 omitted because of collinearity
note: _IBefXSub_1_19 omitted because of collinearity
note: _IBefXSub_1_22 omitted because of collinearity
note: _IBefXSub_1_23 omitted because of collinearity
note: _IBefXSub_1_25 omitted because of collinearity
note: _IBefXSub_1_27 omitted because of collinearity
note: _IBefXSub_1_29 omitted because of collinearity
note: _IBefXSub_1_32 omitted because of collinearity
note: _IBefXSub_1_39 omitted because of collinearity
note: _IBefXSub_1_48 omitted because of collinearity
note: _IBefXSub_1_50 omitted because of collinearity
note: _IBefXSub_1_53 omitted because of collinearity
note: _IBefXSub_1_54 omitted because of collinearity
note: _IBefXSub_1_57 omitted because of collinearity
note: _IBefXSub_1_58 omitted because of collinearity
note: _IBefXSub_1_59 omitted because of collinearity
note: _IBefXSub_1_64 omitted because of collinearity
note: _IBefXSub_1_66 omitted because of collinearity
note: _IBefXSub_1_67 omitted because of collinearity
note: _IBefXSub_1_69 omitted because of collinearity
note: _IBefXSub_1_70 omitted because of collinearity
note: _IBefXSub_1_72 omitted because of collinearity
note: _IBefXSub_1_77 omitted because of collinearity
note: _IBefXSub_1_82 omitted because of collinearity
note: _IBefXSub_1_83 omitted because of collinearity
note: _IBefXSub_1_84 omitted because of collinearity
note: _IBefXSub_1_91 omitted because of collinearity
note: _IBefXSub_1_93 omitted because of collinearity
note: _IBefXSub_1_97 omitted because of collinearity
note: _IBefXSub_1_99 omitted because of collinearity
note: _IBefXSub_1_103 omitted because of collinearity
note: _IBefXSub_1_109 omitted because of collinearity
note: _IBefXSub_1_112 omitted because of collinearity
note: _IBefXSub_1_115 omitted because of collinearity
note: _IBefXSub_1_116 omitted because of collinearity
note: _IBefXSub_1_118 omitted because of collinearity
note: _IBefXSub_1_121 omitted because of collinearity
note: _IBefXSub_1_123 omitted because of collinearity
note: _IBefXSub_1_124 omitted because of collinearity
note: _IBefXSub_1_129 omitted because of collinearity
note: _IBefXSub_1_130 omitted because of collinearity
note: _IBefXSub_1_132 omitted because of collinearity
note: _IBefXSub_1_135 omitted because of collinearity
note: _IBefXSub_1_136 omitted because of collinearity
note: _IBefXSub_1_137 omitted because of collinearity
note: _IBefXSub_1_138 omitted because of collinearity
note: _IBefXSub_1_140 omitted because of collinearity
note: _IBefXSub_1_141 omitted because of collinearity
note: _IBefXSub_1_142 omitted because of collinearity
note: _IBefXSub_1_145 omitted because of collinearity
note: _IBefXSub_1_146 omitted because of collinearity
note: _IBefXSub_1_147 omitted because of collinearity
note: _IBefXSub_1_148 omitted because of collinearity
note: _IBefXSub_1_149 omitted because of collinearity
note: _IBefXSub_1_151 omitted because of collinearity
note: _IBefXSub_1_152 omitted because of collinearity

      Source |       SS           df       MS      Number of obs   =     5,420
-------------+----------------------------------   F(241, 5178)    =      5.00
       Model |  759.869584       241  3.15298583   Prob > F        =    0.0000
    Residual |  3267.68594     5,178  .631071059   R-squared       =    0.1887
-------------+----------------------------------   Adj R-squared   =    0.1509
       Total |  4027.55553     5,419  .743228552   Root MSE        =     .7944

------------------------------------------------------------------------------
          GD |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
 _IBef_Cov_1 |   .0403837   .1124858     0.36   0.720     -.180136    .2609033
 _ISubject_2 |   .5790078   .2924495     1.98   0.048     .0056832    1.152332
 _ISubject_3 |   1.081877   .5676076     1.91   0.057    -.0308735    2.194628
 _ISubject_4 |   .0983613   .2146737     0.46   0.647    -.3224897    .5192124
 _ISubject_5 |   .4022657   .5676076     0.71   0.479    -.7104848    1.515016
 _ISubject_6 |   1.070655   .2770593     3.86   0.000     .5275021    1.613809
 _ISubject_7 |    .564541   .1879572     3.00   0.003     .1960655    .9330164
 _ISubject_8 |   1.699388    .334397     5.08   0.000     1.043828    2.354947
 _ISubject_9 |   -.190753   .1472017    -1.30   0.195    -.4793305    .0978246
_ISubject_10 |   1.367315   .4054758     3.37   0.001     .5724117    2.162219
_ISubject_11 |    .268466   .1785657     1.50   0.133    -.0815981      .61853
_ISubject_12 |  -.8015452   .4054758    -1.98   0.048    -1.596449   -.0066414
_ISubject_13 |   .3488205   .5676076     0.61   0.539      -.76393    1.461571
_ISubject_14 |   .5095864   .3636267     1.40   0.161    -.2032755    1.222448
_ISubject_15 |   -.521534   .1879572    -2.77   0.006    -.8900094   -.1530585
_ISubject_16 |   .8829155    .334397     2.64   0.008     .2273561    1.538475
_ISubject_17 |   1.090305   .2770593     3.94   0.000     .5471513    1.633458
_ISubject_18 |   .6789785    .195439     3.47   0.001     .2958355    1.062121
_ISubject_19 |   .5563469   .2433765     2.29   0.022     .0792263    1.033468
_ISubject_20 |   .4849954   .1065474     4.55   0.000     .2761176    .6938732
_ISubject_21 |   .2072283   .2146737     0.97   0.334    -.2136228    .6280794
_ISubject_22 |   .5779872   .5676076     1.02   0.309    -.5347633    1.690738
_ISubject_23 |   .1929246   .4658325     0.41   0.679    -.7203037    1.106153
_ISubject_24 |   .4537467   .2349187     1.93   0.053    -.0067931    .9142865
_ISubject_25 |   .3488205   .7985699     0.44   0.662    -1.216714    1.914355
_ISubject_26 |   .9958809   .4658325     2.14   0.033     .0826526    1.909109
_ISubject_27 |   1.483437   .7981737     1.86   0.063    -.0813206    3.048194
_ISubject_28 |    .564107   .1732508     3.26   0.001     .2244622    .9037519
_ISubject_29 |   .6988205   .7985699     0.88   0.382    -.8667137    2.264355
_ISubject_30 |   .8686284   .2924495     2.97   0.003     .2953038    1.441953
_ISubject_31 |   .2930706   .1323759     2.21   0.027     .0335578    .5525833
_ISubject_32 |  -.3597179   .3334497    -1.08   0.281     -1.01342    .2939843
_ISubject_33 |  -.0415582   .1587569    -0.26   0.794    -.3527889    .2696724
_ISubject_34 |  -.0906605   .1370359    -0.66   0.508    -.3593087    .1779878
_ISubject_35 |   .5156489   .3644956     1.41   0.157    -.1989164    1.230214
_ISubject_36 |  -.0389771   .2641022    -0.15   0.883    -.5567288    .4787747
_ISubject_37 |  -.0539593   .2042115    -0.26   0.792    -.4543002    .3463815
_ISubject_38 |   .0243902   .1732508     0.14   0.888    -.3152547     .364035
_ISubject_39 |  -.0881054   .3101019    -0.28   0.776    -.6960362    .5198253
_ISubject_40 |  -.1702613   .1879572    -0.91   0.365    -.5387368    .1982141
_ISubject_41 |   .0901286   .1623694     0.56   0.579    -.2281839    .4084412
_ISubject_42 |  -.2221683   .2433765    -0.91   0.361     -.699289    .2549523
_ISubject_43 |   .5250784    .127297     4.12   0.000     .2755225    .7746343
_ISubject_44 |    .667841   .2924495     2.28   0.022     .0945164    1.241166
_ISubject_45 |   .2909626   .2092001     1.39   0.164    -.1191579    .7010831
_ISubject_46 |   .3109127   .1996425     1.56   0.119    -.0804709    .7022962
_ISubject_47 |  -.1756215   .2530078    -0.69   0.488    -.6716236    .3203806
_ISubject_48 |   1.099025   .4054758     2.71   0.007     .3041214    1.893929
_ISubject_49 |   .6962084   .2530078     2.75   0.006     .2002063    1.192211
_ISubject_50 |   .9364461   .7981737     1.17   0.241    -.6283114    2.501204
_ISubject_51 |   .4981219   .1708248     2.92   0.004     .1632332    .8330106
_ISubject_52 |  -.1687164   .2146737    -0.79   0.432    -.5895674    .2521347
_ISubject_53 |   .3084369   .4046949     0.76   0.446     -.484936     1.10181
_ISubject_54 |   .4303625   .1503906     2.86   0.004     .1355334    .7251916
_ISubject_55 |   .3844752   .1497319     2.57   0.010     .0909376    .6780129
_ISubject_56 |   .3859708   .1510767     2.55   0.011     .0897967    .6821449
_ISubject_57 |   .3050296    .155051     1.97   0.049     .0010642    .6089949
_ISubject_58 |   .3084369   .3334497     0.92   0.355    -.3452654    .9621391
_ISubject_59 |   .8973257   .7981737     1.12   0.261    -.6674317    2.462083
_ISubject_60 |   .5236848   .1256535     4.17   0.000     .2773508    .7700188
_ISubject_61 |   .4801169   .1303391     3.68   0.000     .2245972    .7356365
_ISubject_62 |   .2105731    .334397     0.63   0.529    -.4449862    .8661324
_ISubject_63 |  -.0504792   .4054758    -0.12   0.901     -.845383    .7444245
_ISubject_64 |   .3488205   .4658325     0.75   0.454    -.5644077    1.262049
_ISubject_65 |   .5288669   .1915564     2.76   0.006     .1533355    .9043984
_ISubject_66 |  -.3926454   .7981737    -0.49   0.623    -1.957403    1.172112
_ISubject_67 |  -.4011795   .5676076    -0.71   0.480     -1.51393    .7115711
_ISubject_68 |   -.106181   .3644956    -0.29   0.771    -.8207463    .6083844
_ISubject_69 |   .1869855   .2192752     0.85   0.394    -.2428864    .6168574
_ISubject_70 |   .0111583   .3644956     0.03   0.976    -.7034071    .7257236
_ISubject_71 |    .116677   .2042115     0.57   0.568    -.2836639    .5170179
_ISubject_72 |   .3518893   .2092001     1.68   0.093    -.0582312    .7620099
_ISubject_73 |   .4312776   .1623694     2.66   0.008      .112965    .7495902
_ISubject_74 |   .2539471   .1663687     1.53   0.127    -.0722059       .5801
_ISubject_75 |   .3979046   .2207131     1.80   0.071    -.0347862    .8305954
_ISubject_76 |   .6657602   .1708248     3.90   0.000     .3308715    1.000649
_ISubject_77 |   .3488205   .2924495     1.19   0.233     -.224504    .9221451
_ISubject_78 |   .3834464   .4054758     0.95   0.344    -.4114574     1.17835
_ISubject_79 |   .0094722   .2349187     0.04   0.968    -.4510676     .470012
_ISubject_80 |   .2690544   .2349187     1.15   0.252    -.1914854    .7295942
_ISubject_81 |   .0730255    .334397     0.22   0.827    -.5825338    .7285849
_ISubject_82 |   1.942469   .4658325     4.17   0.000     1.029241    2.855697
_ISubject_83 |   .6473728     .56705     1.14   0.254    -.4642846     1.75903
_ISubject_84 |   1.003982   .4651529     2.16   0.031     .0920855    1.915878
_ISubject_85 |   .5271452   .1846097     2.86   0.004     .1652323    .8890581
_ISubject_86 |   .4180132   .1099233     3.80   0.000     .2025172    .6335091
_ISubject_87 |   .8848007   .2641022     3.35   0.001     .3670489    1.402552
_ISubject_88 |   .5764401   .2641022     2.18   0.029     .0586883    1.094192
_ISubject_89 |   .9725988   .2770593     3.51   0.000     .4294456    1.515752
_ISubject_90 |      .8207    .109503     7.49   0.000     .6060278    1.035372
_ISubject_91 |   .3010163   .5676076     0.53   0.596    -.8117342    1.413767
_ISubject_92 |  -.0017304   .1685346    -0.01   0.992    -.3321294    .3286687
_ISubject_93 |   .3769466   .2420732     1.56   0.119    -.0976192    .8515124
_ISubject_94 |   .7286842   .1397206     5.22   0.000     .4547728    1.002596
_ISubject_95 |    .468035   .2530078     1.85   0.064    -.0279671    .9640371
_ISubject_96 |   .4490967   .1623694     2.77   0.006     .1307841    .7674093
_ISubject_97 |   .1106855   .7981737     0.14   0.890    -1.454072    1.675443
_ISubject_98 |   .3344625   .1416683     2.36   0.018     .0567329    .6121921
_ISubject_99 |   .5623923   .1862666     3.02   0.003     .1972312    .9275535
_ISubjec~100 |   1.071685   .4054758     2.64   0.008     .2767815    1.866589
_ISubjec~101 |   .5189012   .1570779     3.30   0.001     .2109623    .8268401
_ISubjec~102 |   .8991862   .3111203     2.89   0.004      .289259    1.509113
_ISubjec~103 |   .2810989   .3334497     0.84   0.399    -.3726034    .9348011
_ISubjec~104 |   .2546882   .1554754     1.64   0.101    -.0501092    .5594857
_ISubjec~105 |  -.1557452   .5676076    -0.27   0.784    -1.268496    .9570054
_ISubjec~106 |   .5619265   .3644956     1.54   0.123    -.1526389    1.276492
_ISubjec~107 |  -.1456385   .1879572    -0.77   0.438    -.5141139    .2228369
_ISubjec~108 |  -.0597556    .334397    -0.18   0.858    -.7153149    .5958038
_ISubjec~109 |   -.021151   .1785657    -0.12   0.906    -.3712151    .3289131
_ISubjec~110 |   .1914784   .1119853     1.71   0.087    -.0280601     .411017
_ISubjec~111 |   .2663299   .2042115     1.30   0.192     -.134011    .6666708
_ISubjec~112 |   .8610239   .3334497     2.58   0.010     .2073217    1.514726
_ISubjec~113 |   1.124312   .1732508     6.49   0.000     .7846677    1.463957
_ISubjec~114 |   .0702242   .2349187     0.30   0.765    -.3903156     .530764
_ISubjec~115 |   .1920329   .5676076     0.34   0.735    -.9207177    1.304783
_ISubjec~116 |   .3560559   .7981737     0.45   0.656    -1.208702    1.920813
_ISubjec~117 |   .2065497   .1685346     1.23   0.220    -.1238493    .5369488
_ISubjec~118 |   .8274255   .2759152     3.00   0.003     .2865152    1.368336
_ISubjec~119 |   .3615867   .1915564     1.89   0.059    -.0139447    .7371182
_ISubjec~120 |   .2983282   .1846097     1.62   0.106    -.0635847    .6602411
_ISubjec~121 |   .3488205   .3644956     0.96   0.339    -.3657448    1.063386
_ISubjec~122 |    .116631   .2530078     0.46   0.645    -.3793711    .6126331
_ISubjec~123 |     .88054   .7981737     1.10   0.270    -.6842174    2.445297
_ISubjec~124 |   .4303458   .2913659     1.48   0.140    -.1408544    1.001546
_ISubjec~125 |   1.612818    .334397     4.82   0.000     .9572591    2.268378
_ISubjec~126 |   .7268422   .5676076     1.28   0.200    -.3859084    1.839593
_ISubjec~127 |   -.777835   .2042115    -3.81   0.000    -1.178176   -.3774941
_ISubjec~128 |   .3820539   .1416683     2.70   0.007     .1043242    .6597835
_ISubjec~129 |   1.907218   .7981737     2.39   0.017     .3424606    3.471976
_ISubjec~130 |   .3488205    .334397     1.04   0.297    -.3067388     1.00438
_ISubjec~131 |   .2526943   .0997341     2.53   0.011     .0571734    .4482153
_ISubjec~132 |  -.3092685   .1689629    -1.83   0.067    -.6405071    .0219701
_ISubjec~133 |   .3488205   .5676076     0.61   0.539      -.76393    1.461571
_ISubjec~134 |   .4165994   .1323759     3.15   0.002     .1570867    .6761121
_ISubjec~135 |   .3987385   .2759152     1.45   0.148    -.1421719    .9396488
_ISubjec~136 |   1.371485   .3636267     3.77   0.000     .6586231    2.084347
_ISubjec~137 |   .2200192   .1585357     1.39   0.165    -.0907777    .5308161
_ISubjec~138 |   .9035384   .1797354     5.03   0.000      .551181    1.255896
_ISubjec~139 |  -.5769611    .127297    -4.53   0.000     -.826517   -.3274051
_ISubjec~140 |   .3404925   .1121778     3.04   0.002     .1205767    .5604084
_ISubjec~141 |   .3488205   .4054758     0.86   0.390    -.4460832    1.143724
_ISubjec~142 |   .3964209   .2629017     1.51   0.132    -.1189774    .9118193
_ISubjec~143 |   .4457341   .2274189     1.96   0.050     -.000103    .8915711
_ISubjec~144 |   .7443925   .3111203     2.39   0.017     .1344653     1.35432
_ISubjec~145 |   .5882206     .56705     1.04   0.300    -.5234368    1.699878
_ISubjec~146 |   .3488205   .7985699     0.44   0.662    -1.216714    1.914355
_ISubjec~147 |   .3488205   .7985699     0.44   0.662    -1.216714    1.914355
_ISubjec~148 |   .3488205   .7985699     0.44   0.662    -1.216714    1.914355
_ISubjec~149 |   1.719399   .4651529     3.70   0.000     .8075029    2.631295
_ISubjec~150 |   .3669586   .1758261     2.09   0.037     .0222652     .711652
_ISubjec~151 |   1.822306   .2274189     8.01   0.000     1.376469    2.268143
_ISubjec~152 |   1.188963   .2433765     4.89   0.000     .7118419    1.666083
_IBefXSub~_2 |  -.3404369   .3742738    -0.91   0.363    -1.074172    .3932978
_IBefXSub~_3 |          0  (omitted)
_IBefXSub~_4 |   .3046593   .2952194     1.03   0.302    -.2740954     .883414
_IBefXSub~_5 |   .2968213   .8023242     0.37   0.711    -1.276073    1.869716
_IBefXSub~_6 |          0  (omitted)
_IBefXSub~_7 |  -.3302675   .2671874    -1.24   0.216    -.8540676    .1935326
_IBefXSub~_8 |          0  (omitted)
_IBefXSub~_9 |   .0786325   .1989612     0.40   0.693    -.3114155    .4686804
_IBefXSu~_10 |          0  (omitted)
_IBefXSu~_11 |  -.3852507   .2666649    -1.44   0.149    -.9080265    .1375251
_IBefXSu~_12 |          0  (omitted)
_IBefXSu~_13 |  -.0638126   .5858448    -0.11   0.913    -1.212316     1.08469
_IBefXSu~_14 |          0  (omitted)
_IBefXSu~_15 |   .1144365   .2580328     0.44   0.657    -.3914168    .6202898
_IBefXSu~_16 |  -.4972814   .4128206    -1.20   0.228    -1.306584    .3120212
_IBefXSu~_17 |          0  (omitted)
_IBefXSu~_18 |   .2717055    .318711     0.85   0.394    -.3531027    .8965136
_IBefXSu~_19 |          0  (omitted)
_IBefXSu~_20 |  -.0407391   .1473593    -0.28   0.782    -.3296255    .2481473
_IBefXSu~_21 |   .3234308   .3965772     0.82   0.415     -.454028     1.10089
_IBefXSu~_22 |          0  (omitted)
_IBefXSu~_23 |          0  (omitted)
_IBefXSu~_24 |   .5248567   .3742738     1.40   0.161    -.2088779    1.258591
_IBefXSu~_25 |          0  (omitted)
_IBefXSu~_26 |   .1681578   .5728775     0.29   0.769     -.954924    1.291239
_IBefXSu~_27 |          0  (omitted)
_IBefXSu~_28 |   .1043893   .2794592     0.37   0.709    -.4434688    .6522474
_IBefXSu~_29 |          0  (omitted)
_IBefXSu~_30 |  -.6949496   .4666381    -1.49   0.136    -1.609757    .2198581
_IBefXSu~_31 |   .2457617   .2079773     1.18   0.237    -.1619617     .653485
_IBefXSu~_32 |          0  (omitted)
_IBefXSu~_33 |   .0305555   .2197042     0.14   0.889    -.4001575    .4612685
_IBefXSu~_34 |   .1035785   .1874419     0.55   0.581    -.2638868    .4710438
_IBefXSu~_35 |  -.0611026   .4785606    -0.13   0.898    -.9992835    .8770783
_IBefXSu~_36 |   .2327175    .372649     0.62   0.532    -.4978319    .9632668
_IBefXSu~_37 |   .2582088   .3102523     0.83   0.405    -.3500167    .8664343
_IBefXSu~_38 |   .2129398   .2704587     0.79   0.431    -.3172733     .743153
_IBefXSu~_39 |          0  (omitted)
_IBefXSu~_40 |   .2290901   .2939636     0.78   0.436    -.3472027    .8053829
_IBefXSu~_41 |   .0139382   .2445647     0.06   0.955    -.4655118    .4933883
_IBefXSu~_42 |   .0896881   .3275877     0.27   0.784    -.5525222    .7318983
_IBefXSu~_43 |  -.0442891   .1809215    -0.24   0.807    -.3989717    .3103934
_IBefXSu~_44 |   .0200217   .4435262     0.05   0.964    -.8494768    .8895202
_IBefXSu~_45 |  -.0427148   .2778718    -0.15   0.878     -.587461    .5020313
_IBefXSu~_46 |   -.006687   .2707493    -0.02   0.980      -.53747    .5240959
_IBefXSu~_47 |  -.0176647    .316345    -0.06   0.955    -.6378345     .602505
_IBefXSu~_48 |          0  (omitted)
_IBefXSu~_49 |   -.569067   .4772745    -1.19   0.233    -1.504726    .3665925
_IBefXSu~_50 |          0  (omitted)
_IBefXSu~_51 |   .1492011    .238647     0.63   0.532    -.3186477    .6170499
_IBefXSu~_52 |   .1603262     .36191     0.44   0.658    -.5491703    .8698227
_IBefXSub~53 |          0  (omitted)
_IBefXSub~54 |          0  (omitted)
_IBefXSub~55 |  -.0460268   .2339326    -0.20   0.844    -.5046334    .4125799
_IBefXSub~56 |   .0498076   .2217916     0.22   0.822    -.3849975    .4846127
_IBefXSub~57 |          0  (omitted)
_IBefXSub~58 |          0  (omitted)
_IBefXSub~59 |          0  (omitted)
_IBefXSub~60 |   -.198687    .181302    -1.10   0.273    -.5541156    .1567415
_IBefXSub~61 |  -.0992183   .1775569    -0.56   0.576    -.4473049    .2488683
_IBefXSub~62 |   1.336734   .6583062     2.03   0.042      .046176    2.627292
_IBefXSub~63 |    -.46217   .5446421    -0.85   0.396    -1.529899    .6055585
_IBefXSub~64 |          0  (omitted)
_IBefXSub~65 |    .158288   .2587973     0.61   0.541    -.3490639    .6656399
_IBefXSub~66 |          0  (omitted)
_IBefXSub~67 |          0  (omitted)
_IBefXSub~68 |  -.3218001   .6740941    -0.48   0.633    -1.643309    .9997088
_IBefXSub~69 |          0  (omitted)
_IBefXSub~70 |          0  (omitted)
_IBefXSub~71 |   .1012585   .2996397     0.34   0.735    -.4861619    .6886789
_IBefXSub~72 |          0  (omitted)
_IBefXSub~73 |  -.0704443   .2400351    -0.29   0.769    -.5410145     .400126
_IBefXSub~74 |    .489913   .2806515     1.75   0.081    -.0602825    1.040108
_IBefXSub~75 |  -.2546125   .2996397    -0.85   0.396    -.8420329    .3328078
_IBefXSub~76 |  -.4165194   .3042391    -1.37   0.171    -1.012956    .1799176
_IBefXSub~77 |          0  (omitted)
_IBefXSub~78 |  -.1670634   .5104643    -0.33   0.743    -1.167789    .8336622
_IBefXSub~79 |   -.241739   .4078915    -0.59   0.553    -1.041379    .5579006
_IBefXSub~80 |   .1288816   .3135583     0.41   0.681    -.4858251    .7435882
_IBefXSub~81 |   .2560786    .418571     0.61   0.541    -.5644973    1.076654
_IBefXSub~82 |          0  (omitted)
_IBefXSub~83 |          0  (omitted)
_IBefXSub~84 |          0  (omitted)
_IBefXSub~85 |   .3698534   .2648432     1.40   0.163    -.1493511     .889058
_IBefXSub~86 |   .0510889   .1528144     0.33   0.738    -.2484919    .3506697
_IBefXSub~87 |  -.5833404   .3648702    -1.60   0.110     -1.29864    .1319593
_IBefXSub~88 |  -.1661097    .372649    -0.45   0.656    -.8966591    .5644396
_IBefXSub~89 |   .1952864   .3679148     0.53   0.596     -.525982    .9165548
_IBefXSub~90 |   .0991499   .1561268     0.64   0.525    -.2069245    .4052243
_IBefXSub~91 |          0  (omitted)
_IBefXSub~92 |  -.4415763   .2290081    -1.93   0.054    -.8905289    .0073764
_IBefXSub~93 |          0  (omitted)
_IBefXSub~94 |  -.1017117   .2157956    -0.47   0.637    -.5247623    .3213389
_IBefXSub~95 |   .4494516   .3348052     1.34   0.180     -.206908    1.105811
_IBefXSub~96 |   .2503374   .2311054     1.08   0.279    -.2027269    .7034017
_IBefXSub~97 |          0  (omitted)
_IBefXSub~98 |   .0502731    .196097     0.26   0.798    -.3341598    .4347061
_IBefXSub~99 |          0  (omitted)
_IBefXSu~100 |   .4245753   .6971057     0.61   0.543    -.9420462    1.791197
_IBefXSu~101 |   .1274174   .2274189     0.56   0.575    -.3184197    .5732545
_IBefXSu~102 |  -.0498967   .5104643    -0.10   0.922    -1.050622    .9508289
_IBefXSu~103 |          0  (omitted)
_IBefXSu~104 |   .1683081   .2163098     0.78   0.437    -.2557504    .5923667
_IBefXSu~105 |  -.4034755   .7338567    -0.55   0.582    -1.842144    1.035193
_IBefXSu~106 |  -.0453938    .590952    -0.08   0.939    -1.203909    1.113122
_IBefXSu~107 |   .1609158   .2527377     0.64   0.524    -.3345568    .6563885
_IBefXSu~108 |  -.0608188   .4722394    -0.13   0.898    -.9866074    .8649699
_IBefXSu~109 |          0  (omitted)
_IBefXSu~110 |  -.0300299   .1576757    -0.19   0.849    -.3391408     .279081
_IBefXSu~111 |   .4277022   .3102523     1.38   0.168    -.1805232    1.035928
_IBefXSu~112 |          0  (omitted)
_IBefXSu~113 |   .5323247   .2666188     2.00   0.046     .0096394     1.05501
_IBefXSu~114 |   .2409125   .4078915     0.59   0.555    -.5587271    1.040552
_IBefXSu~115 |          0  (omitted)
_IBefXSu~116 |          0  (omitted)
_IBefXSu~117 |  -.4847333   .2717647    -1.78   0.075    -1.017507    .0480404
_IBefXSu~118 |          0  (omitted)
_IBefXSu~119 |  -.1609583   .2911623    -0.55   0.580    -.7317593    .4098427
_IBefXSu~120 |  -.3334585   .2820157    -1.18   0.237    -.8863284    .2194114
_IBefXSu~121 |          0  (omitted)
_IBefXSu~122 |  -.0940049   .3086519    -0.30   0.761     -.699093    .5110831
_IBefXSu~123 |          0  (omitted)
_IBefXSu~124 |          0  (omitted)
_IBefXSu~125 |   -.743829   .4335327    -1.72   0.086    -1.593736    .1060781
_IBefXSu~126 |  -.0156206   .6740941    -0.02   0.982     -1.33713    1.305888
_IBefXSu~127 |   .2332842   .2952194     0.79   0.429    -.3454705    .8120388
_IBefXSu~128 |   -.033788    .199497    -0.17   0.866    -.4248863    .3573103
_IBefXSu~129 |          0  (omitted)
_IBefXSu~130 |          0  (omitted)
_IBefXSu~131 |  -.1208454   .1706001    -0.71   0.479    -.4552936    .2136029
_IBefXSu~132 |          0  (omitted)
_IBefXSu~133 |  -.6911229   .5810401    -1.19   0.234    -1.830207    .4479609
_IBefXSu~134 |   .0340575   .2232223     0.15   0.879    -.4035526    .4716675
_IBefXSu~135 |          0  (omitted)
_IBefXSu~136 |          0  (omitted)
_IBefXSu~137 |          0  (omitted)
_IBefXSu~138 |          0  (omitted)
_IBefXSu~139 |  -.6426129   .2483076    -2.59   0.010    -1.129401   -.1558251
_IBefXSu~140 |          0  (omitted)
_IBefXSu~141 |          0  (omitted)
_IBefXSu~142 |          0  (omitted)
_IBefXSu~143 |   .4725805   .3159129     1.50   0.135    -.1467422    1.091903
_IBefXSu~144 |  -.2647448   .4158426    -0.64   0.524    -1.079972    .5504823
_IBefXSu~145 |          0  (omitted)
_IBefXSu~146 |          0  (omitted)
_IBefXSu~147 |          0  (omitted)
_IBefXSu~148 |          0  (omitted)
_IBefXSu~149 |          0  (omitted)
_IBefXSu~150 |   .1325574   .2763457     0.48   0.631    -.4091969    .6743117
_IBefXSu~151 |          0  (omitted)
_IBefXSu~152 |          0  (omitted)
       _cons |  -.3488205   .0815037    -4.28   0.000    -.5086022   -.1890389
-
WIL_reg.xml
dir : seeout

Sorry for the long output, I want to ensure that there is as little confusion in my post.

Regards,
Bannin

[Carlo Lazzaro]

Bannin:
1) I still do not undderstand your code, that creates many omission due to perfect collinearity. In addition, you invoked -robust- standard error to deal with heteroskedsticity, but your output table shows default standard errors instead;
2) provided what above, once the string variable has been -destring-, your code should be:

 
 reg GD i.Bef_Cov##i.Subject, robust

;
3) I would check via -linktest- if your model is not misspecified.

[Bannin William]

Thank you for your help Carlo, I will make use of your recommendations.

Cheers,
Bannin