[R-meta] correlation between pre and post test?

Philippe Tadger ph|||ppet@dger @end|ng |rom gm@||@com
Wed Aug 25 14:54:41 CEST 2021

Dear YA

You can use correlation imputations from similar studies, or if this is 
not available you can use a mean difference estimation (not SMD) between 
the post and the change scores. If all the studies present pre and post 
(and you don't have any study with change score) you can do a SMD only 
using the post measures. All of this are common practices that you can 
find in Cochrane book, and basic MA books.

On 25/08/2021 14:45, Michael Dewey wrote:
> If you are planning to analyse the change scores you will be OK with 
> the mean change and its standard error. Otherwise try fitting with a 
> range of plausible correlations and see how sensitive the results are 
> to the assumed value.
> Michael
> On 25/08/2021 04:28, YA wrote:
>> Dear list,
>> I am trying to do meta analysis with random control trial research 
>> that has experiment and control group, and pre and post test. 
>> According to the meta analysis books, for these kind of research, I 
>> need the mean and SD for the experiment and control group at both pre 
>> and post test, I also need the correlation between pre and post test. 
>> The means and SDs are usually reported by the authors, but the 
>> correlations are usually not reported. How do I obtain the 
>> correlations between the pre and the post test?
>> Thank you very much.
>> Best regards,
>> YA
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Kind regards/Saludos cordiales
*Philippe Tadger*
ORCID <https://orcid.org/0000-0002-1453-4105>, Reseach Gate 
Phone/WhatsApp: +32498774742

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