st: Subgroup analysis

[David Bai <db555@mail.com>]

Hi, all,
    I would like to compare predictors' effects across different 
racial/ethnic groups, so I first ran a comprehensive model including 
all groups, and then used subpop function in stata to do subpopulation 
analyses for each ethnic group.
   What the results show is that many (not just a few) significant 
predictors in the comprehensive model (including all racial groups) 
become non-significant in the African American group, while the White 
group's results are similar to the results of the comprehensive model. 
How can I interpret all these? Is it possibly because African Americans 
are very homogeneous in the distributions of these predictors, and 
therefore it is hard for the analysis to distinguish any variations in 
the effects and therefore find non-significance in the results? Or is 
it because the sample size of this group is relatively small compared 
with other groups (e.g., whites)  in the sample? Are there any other 
possible interpretations? Your insight will be appreciated.

     David B






 

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