Re: st: warning: overlapping samples

[Steven Samuels <ssamuels@albany.edu>]

Dear ncd:

Your example data set below is not helpful because it did not   
generate the output that you originally displayed. See Statalist FAQ:  
http://www.stata.com/support/faqs/res/statalist.html .

"Say exactly what you typed and exactly what Stata typed (or did) in  
response. N.B. exactly!"

 In your "example",  the data appear to be in "wide" format in which  
all variables for husbands and wives are on the same line.  -oaxaca-  
is intended to be used if you regress "hwage" and "wwage" on the same  
"X" variables.  But, if you had done that, then only the "coeffient"  
portion of the decomposition would have been present, as the X means  
would be identical for men and women.  Yet your output showed non- 
zero values for the other components. So, what did you actually do?

-Steven


On Jun 28, 2007, at 10:01 AM, ncdcta00@uniroma2.it wrote:


> Thanks Ben, I don't know why? because I want calculate the  
> decoposition between husband and wife, so sure I have relation  
> because  my dataset is:
> wife   husband  wwage hwage
> 1       1          100  200
> I do :
> reg wwage xi
> est stor w
> reghwage xi
> est sto h
> oaxaca h w
>
>
> Can I estimate with oaxaca this data set? is it right the procedure?
> thanks a lot for your help.
>
>
>
> Quoting Ben Jann <ben.jann@gmail.com>:
>
>
> > It means that some of your females are in the male sample or vice
> > versa. Check the -if- qualifiers of your regression commands.
> > ben
> >
> > On 6/28/07, ncdcta00@uniroma2.it <ncdcta00@uniroma2.it> wrote:
> > > Dear statalist, I'm doing a oaxaca decomposition and I have this
> > > message before the estmation with oaxaca. What is it means?
> > > thanks
> > > warning: overlapping samples
> > > (high estimates: female4; low estimates: male4)
> > >
> > >                                                  Mean prediction  
> > > 1  =  2.095566
> > >                                                  Mean prediction  
> > > 2  =  1.939635
> > > -------------------------------------------------------------------- 
> > > ----------
> > >              |      Coef.   Std. Err.      z    P>|z|     [95%   
> > > Conf. Interval]
> > > ------------- 
> > > +----------------------------------------------------------------
> > >   difference |    .155931   .0301257     5.18   0.000     . 
> > > 0968858     .2149762
> > > -------------------------------------------------------------------- 
> > > ----------
> > >
> > > Linear decomposition
> > > -------------------------------------------------------------------- 
> > > ----------
> > >        Total |      Coef.   Std. Err.      z    P>|z|     [95%   
> > > Conf. Interval]
> > > ------------- 
> > > +----------------------------------------------------------------
> > > three-fold   |
> > >   endowments |  -.6220027   .2610409    -2.38   0.017     
> > > -1.133633     -.110372
> > > coefficients |  -.1470742   .0839665    -1.75   0.080    -. 
> > > 3116456     .0174971
> > >  interaction |   .9250079   .2727451     3.39   0.001     . 
> > > 3904373     1.459579
> > > -------------------------------------------------------------------- 
> > > ----------
> > >
> > >
> > >
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