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st: RE: metan with repeated-measures designs?


From   "Ploutz-Snyder, Robert (JSC-SK)[USRA]" <robert.ploutz-snyder-1@nasa.gov>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: RE: metan with repeated-measures designs?
Date   Fri, 23 Jul 2010 13:33:39 -0500

Statalisters,
Please forgive my re-post, but I'm hoping there's a gem of info out there??

I'm looking for help using -matan- (or other) command for meta analysis of studies that all used repeated measures designs.  In the most simple form, I'd like to be able to estimate an across-studies effect for Pre/Post differences when all I can extract from the literature are means and SD pre and post for several studies (i.e. no mean difference score with SD-diff were reported in any studies).

-metan- is great, but it's written for independent groups designs...  is there a way to accommodate repeated-measures designs with -metan- or other user-written commands?  

Rob

-----Original Message-----
From: Ploutz-Snyder, Robert (JSC-SK)[USRA] 
Sent: Thursday, July 22, 2010 3:56 PM
To: 'statalist@hsphsun2.harvard.edu'
Subject: metan with repeated-measures designs?

Good afternoon Statalisters;

I am considering a meta analysis of studies that were all similarly designed as 2-factor, completely repeated measures factorials. The outcome of interest is continuous/normal.
 
The two factors are Time (pre, post) and Leg (left, right), where an experimental intervention was applied to one leg per human subject, with their other leg serving as (obviously within-subject) control.  Thus each study is a straight forward 2(time) x 2(leg) completely within-subjects factorial design, and I'm hoping to get a meta analytic estimate of across-study effects.  I'd also like to factor in a couple of covariates (study sample size, duration of the intervention) eventually.

As typical of meta analytic projects, the various papers don't supply me with all that I'd like. Most, however, report means(SD) of the continuously scaled outcomes,  pre and post, for each leg.  So I can construct a dataset that is kinda/sorta like the data that user-written -metan- command would typically use.


My admittedly meager understanding of the -metan- command is that it is designed for completely independent measures design, and furthermore with only one mean(sd) and n per group.  Is there a method for somehow adjusting for the repeated-measures design if I feed -metan- the pre and post means and SD of only my TREATED leg (ignoring the already established null change in control legs).  Is it possible to expand to a two factor design?  

I'm open to any thoughts on a better approach for meta analysis with this sort of experimental design??

Much obliged.




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