Hi,

I am trying to graph my results using the margins command, however, it returns the "not estimable" error. I have tried the advice here (https://www.statalist.org/forums/for...-not-estimable) but it does not work for me.

Code:
areg C1 i.sonbirth##i.year [pweight= panel_wt_06_12_18] , absorb(Findid)
(sum of wgt is 7,684.09828691185)
note: 1.sonbirth omitted because of collinearity

Linear regression, absorbing indicators         Number of obs     =      8,535
Absorbed variable: Findid                       No. of categories =      3,540
                                                F(   4,   4991)   =      52.86
                                                Prob > F          =     0.0000
                                                R-squared         =     0.5036
                                                Adj R-squared     =     0.1513
                                                Root MSE          =     1.3278

-------------------------------------------------------------------------------
              |               Robust
           C1 |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
--------------+----------------------------------------------------------------
   1.sonbirth |          0  (omitted)
              |
         year |
           1  |  -.2650297   .1069619    -2.48   0.013    -.4747219   -.0553374
           2  |   .4925483   .1156093     4.26   0.000     .2659033    .7191934
              |
sonbirth#year |
         1 1  |   .2409295   .1152284     2.09   0.037     .0150313    .4668278
         1 2  |   .0648046   .1315297     0.49   0.622    -.1930513    .3226606
              |
        _cons |  -.0330636   .0355901    -0.93   0.353    -.1028359    .0367087
-------------------------------------------------------------------------------

. margins sonbirth##year

Predictive margins                              Number of obs     =      8,535
Model VCE    : Robust

Expression   : Linear prediction, predict()

-------------------------------------------------------------------------------
              |            Delta-method
              |     Margin   Std. Err.      t    P>|t|     [95% Conf. Interval]
--------------+----------------------------------------------------------------
     sonbirth |
           0  |          .  (not estimable)
           1  |          .  (not estimable)
              |
         year |
           0  |  -.0330636   .0355901    -0.93   0.353    -.1028359    .0367087
           1  |    -.12697   .0259481    -4.89   0.000    -.1778397   -.0761003
           2  |    .505513   .0400142    12.63   0.000     .4270676    .5839585
              |
sonbirth#year |
         0 0  |          .  (not estimable)
         0 1  |          .  (not estimable)
         0 2  |          .  (not estimable)
         1 0  |          .  (not estimable)
         1 1  |          .  (not estimable)
         1 2  |          .  (not estimable)
-------------------------------------------------------------------------------
Not sure how to resolve this.