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Re: st: warning: overlapping samples


From   Steven Samuels <ssamuels@albany.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: warning: overlapping samples
Date   Thu, 28 Jun 2007 13:36:06 -0400

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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