st: warning: overlapping samples

[ncdcta00@uniroma2.it]

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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