R help - Mar 2013 - 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]]

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 K?sters
> 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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