[R] Metafor "SMCR" Pre-Post Effect sizes

[Markus Kösters]

Dear Wolfgang,

Thank you for your clarification - and your excellent package !

Best wishes,

Markus

-----Ursprüngliche Nachricht-----
Von: Viechtbauer Wolfgang (STAT)
[mailto:wolfgang.viechtbauer at maastrichtuniversity.nl] 
Gesendet: Montag, 4. März 2013 10:45
An: Markus Kösters; R-help at r-project.org
Betreff: RE: [R] Metafor "SMCR" Pre-Post Effect sizes

Absolutely correct. The documentation wasn't clear on that. Changed for the
next version of the package. And the escalc() function now no longer checks
for sd2i, since it is not needed anyway (for "SMCR"). For now, you will just
have to set sd2i to something (e.g., 0).

Thanks for bringing this to my attention!

Best,
Wolfgang

--   
Wolfgang Viechtbauer, Ph.D., Statistician   
Department of Psychiatry and Psychology   
School for Mental Health and Neuroscience   
Faculty of Health, Medicine, and Life Sciences   
Maastricht University, P.O. Box 616 (VIJV1)   
6200 MD Maastricht, The Netherlands   
+31 (43) 388-4170 | http://www.wvbauer.com   


> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org]
> On Behalf Of Markus Kösters
> Sent: Saturday, March 02, 2013 23:31
> To: R-help at r-project.org
> Subject: [R] Metafor "SMCR" Pre-Post Effect sizes
> 
> Dear all,
> 
> I am very grateful that Wolfgang Viechtbauer implemented the 
> standardised mean change for dependent groups. I was playing around a 
> bit today, and I am not sure if I understand the "SMCR" procedure 
> correctly. The documentation states that sd1i and sd2i are needed, but 
> it seems to me that SMCR is ignoring sd2i (so Variances are not 
> pooled). Instead, it uses sd1i (pre-test sd), as suggested by Becker 
> 1988. Is that correct?
> 
> Thank you all very much for your time and help,
> 
> Markus
> 
> 	[[alternative HTML version deleted]]
> 
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