> The problem is, we want to perform a mean comparison between
> two variables
> (paired t-test) and not between two subgroups. The syntax
> without adjusting
> for the clustering is "ttest var1=var2", thus using inflated
> degrees of
> freedom, 'cause no adjustment for the clustering of the data
> is possible.
> In contrast performing the test with a disaggregated file
> would result in
> deflated degrees of freedom...
> For our group comparisons we exactly use your proposition.
Rich Goldstein
> >a t-test is a simple regression where the only predictor is the dummy
> >variable identifying the groups -- so, put the two variables
> into one long
> >variable; add a group identifier and use regression with the
> cluster option
Christian Hunkler
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