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st: Re: Adjusting confidence intervals


From   Joseph Coveney <jcoveney@bigplanet.com>
To   Statalist <statalist@hsphsun2.harvard.edu>
Subject   st: Re: Adjusting confidence intervals
Date   Wed, 13 Oct 2004 13:25:24 +0900

Ilesh Patel wrote:

I have computed a difficulty score for a range of vision tasks and want to
see if there is a difference in the mean score by self-rated overall health
(scored from 1 =AD 4). Following is what I used:

Sort overall_hlth

by overall_hlth: ci diff_score

This gives me the mean difficulty score and it=B9s CI for each of the 4
self-rated overall health groups. What command do I use in Stata to adjust
the CI for age given that I think age affects both the difficulty score.

----------------------------------------------------------------------------

The nature of the adjustment that you'd do would depend upon what you
believe the nature of the functional relationship is between age and
difficulty score.  In the simple case, it seems that you could first
use -regress-, with both age and overall health self-rating score as
predictors (independent variables), and then -adjust-; the latter has a -ci-
option.

If, on the other hand, you meant to write ". . . age affects both the
difficulty score *and the overall health self-rating score*," then you have
issues for which others on the list will be capable to help.

Joseph Coveney




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