Re: st: -mfx-: can I just keep the interaction variable?

[Scott Cunningham <scunning@gmail.com>]

Richard,

The dataset is the NLSY97, selection just on males, blacks and whites  
only, and balanced for the 1997-2002.  Here's the entire code, plus  
output.  I'm going to snip the fixed effects, though.

. xi:xtpoisson rp i.race age age2 hgc hhd1 i.year i.fip, vce(boot);
i.race            _Irace_1-2          (naturally coded; _Irace_1  
omitted)
i.year            _Iyear_1997-2002    (naturally coded; _Iyear_1997  
omitted)
i.fip             _Ifip_1-56          (naturally coded; _Ifip_1 omitted)
(running xtpoisson on estimation sample)

Bootstrap replications (50)
----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5
.............x..x..x....x.x.....x..............x..    50

Random-effects Poisson regression               Number of obs       
=     27591
Group variable (i): id                          Number of groups    
=      4637

Random effects u_i ~ Gamma                      Obs per group: min  
=         1
                                                               avg  
=       6.0
                                                               max  
=         6

                                                Wald chi2(42)       
=         .
Log likelihood  = -38560.683                    Prob > chi2         
=         .

------------------------------------------------------------------------ 
------
             |   Observed   Bootstrap                         Normal- 
based
          rp |      Coef.   Std. Err.      z    P>|z|     [95% Conf.  
Interval]
------------- 
+----------------------------------------------------------------
    _Irace_2 |   .3327858   .0475309     7.00   0.000      . 
239627    .4259445
         age |   2.558144   .1699299    15.05   0.000      
2.225088    2.891201
        age2 |  -.0644527   .0045961   -14.02   0.000    -.0734609    
-.0554444
         hgc |   .0806298   .0302402     2.67   0.008       . 
02136    .1398996
        hhd1 |  -.1316166   .0890242    -1.48   0.139    -. 
3061008    .0428676

-- SNIP --

    _Ifip_56 |  -.5006855   2.752276    -0.18   0.856     
-5.895047    4.893675
       _cons |   -25.3175   1.456052   -17.39   0.000    -28.17131    
-22.46369
------------- 
+----------------------------------------------------------------
    /lnalpha |   .3708587   .0435552                      . 
2854922    .4562253
------------- 
+----------------------------------------------------------------
       alpha |   1.448978   .0631105                       
1.330417    1.578106
------------------------------------------------------------------------ 
------
Likelihood-ratio test of alpha=0: chibar2(01) =  3.3e+04  
Prob>=chibar2 = 0.000
Note: One or more parameters could not be estimated in 7 bootstrap  
replicates; standard error
      estimates include only complete replications.

. mfx, dydx varlist(_Irace_2 age age2 hgc hhd1);
no observations
r(2000);

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/