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

[YA]

Hi everyone, 


Thank you very much for the helpful suggestions.


Philippe:


By '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', do you mean use post SD as the standardizer to calculate the SMD?


Michael:


1. If I use change scores as the effect size, can I use the pre and post means and SDs to calculate the effect size and the standard error?


2. By using a range of plausible pre-post correlations for a sensitivity analysis, do you mean providing a correlation coefficient for all of primary studies and save the results, then change the correlation coefficient to another value for all the primary studies, and run the analysis again, see if the two sets of results are significantly different? Is it possible to do the significant test?


Mike:


I do not have access to SAS or Stata, do you know any R implementation example code using Riley(2008) method? 


Thank you very much guys.


Best regards,


YA




------------------ Original ------------------
From:                                                                                                                        "Philippe Tadger"                                                                                    <philippetadger using gmail.com>;
Date: Wed, Aug 25, 2021 08:54 PM
To: "Michael Dewey"<lists using dewey.myzen.co.uk>;"YA"<xinxi813 using 126.com>;"r-sig-meta-analysis"<r-sig-meta-analysis using r-project.org>;

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



                   
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         
             [[alternative HTML version deleted]]         
         
         _______________________________________________         
         R-sig-meta-analysis mailing list         
         R-sig-meta-analysis using r-project.org         
         https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis         
         
              
          -- 
       Kind regards/Saludos cordiales 
       Philippe Tadger 
       ORCID, Reseach         Gate 
       Phone/WhatsApp: +32498774742
	[[alternative HTML version deleted]]