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# st: RE: "Repeated-measures" form of linear regression?

 From "Cohen, Elan" To "'statalist@hsphsun2.harvard.edu'" Subject st: RE: "Repeated-measures" form of linear regression? Date Fri, 17 Sep 2010 16:59:04 -0400

```Pietro,

See -xtreg-.  In your case, something like:

xtreg D F, i(subject)

- Elan

> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of
> Pietro Mazzoni
> Sent: Friday, September 17, 2010 16:41
> To: statalist@hsphsun2.harvard.edu
> Subject: st: "Repeated-measures" form of linear regression?
>
> Dear Statalist,
>
> My question is not specific to Stata, but I am hoping that
> someone can at least point me to the topic of statistical
> testing on which I can do more reading to answer this
> question. I appreciate any suggestions.
>
> My hypothesis, in a motor control experiment, is that there
> is a linear relationship between a perturbation (say, force
> F) and a response (say, lateral deviation D). I obtained data
> from several subjects who were tested at various levels of
> force and whose response was a particular deviation for each
> force pulse. I feel that it would be incorrect to perform a
> linear regression of D vs. F on the pooled data, because this
> would ignore within-subject correlations. I see this data as
> analogous to repeated-measures ANOVA, because multiple pairs
> of (F, D) were collected within each subject.  So my
> intuition tells me I should perform linear regression within
> each subject, and then somehow combine these results across
> the group, but I don't know what procedure might be the
> analog of rm-ANOVA for regression. One suggestion I got was
> to perform individual regressions within each subject and
> then average the values of the slopes and intercepts obtained
> to estimate slope and intercept f!
>  or the group. But I am more interested in establishing
> whether there is a significant relationship at the group
> level (R square, p value for the group) than in determining
> the parameters of the regression, and I don't know how to
> combine the R squares or p values obtained for individual subjects.
>
> continuous variables/regression?
>
> Thanks in advance for any ideas.
>
> Pietro
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```