-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of petretta at unina.it
Sent: Thursday, November 21, 2013 13:39
To: r-help at r-project.org
Subject: [R] metafor escalc(measure="SMCC")
Many thanks to Wolfgang Viechtbauer for the prompt and clear answer.
However, I'm unable to understand what .cmicalc mathematically does in the
code line:
cmi <- .cmicalc(mi)
I look in the metafor documentation and in R (?.cmical and ??.cmicalc) but
I have no result. Please, can I have further explanation on this point?
Sorry for the trouble
Sincerely
Mario Petretta
Department of Translational Medical Sciences
Naples University Federico II
Italy
Message: 50
Date: Tue, 19 Nov 2013 11:48:33 +0100
From: "Viechtbauer Wolfgang (STAT)"
<wolfgang.viechtbauer at maastrichtuniversity.nl>
To: "petretta at unina.it" <petretta at unina.it>, "r-help at r-project.org"
<r-help at r-project.org>
Subject: Re: [R] metafor escalc(measure="SMCC")
Message-ID:
<077E31A57DA26E46AB0D493C9966AC730D9925568A at UM-
MAIL4112.unimaas.nl>
Content-Type: text/plain; charset="us-ascii"
Dear Mario,
You can always just inspect the code:
escalc.default
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 petretta at unina.it
Sent: Tuesday, November 19, 2013 11:29
To: r-help at r-project.org
Subject: [R] metafor escalc(measure="SMCC")
Dear all,
I use R 3.0 for Windows.
I ask how escalc(measure="SMCC") [metafor package] mathematically
calculate yi and vi when only change score and SD change score are
provided.
I used the example (repoted below) posted by Qiang Yue at:
http://r.789695.n4.nabble.com/using-metafor-for-meta-analysis-of-before-
after-studies-escalc-SMCC-td4667233.html
but it is unclear for me the formula used to derive y1 and v1. I read
the documentation of metafor package and it is all very well
described, but I ask if possible for the formula used by
escalc(measure="SMCC") to mathematically calculate yi and vi.
Unfortunatel, I have no free access to the paper quoted in metafor
package.
Beginning example:
fMRS
author year n mean_r sd_r mean_s sd_s r
1 Tom 2006 9 0 0 0.12 0.03 0 0
2 Jack 2012 6 0 0 0.23 0.05 0 0
3 Zhu 2013 8 0 0 0.18 0.05 0 0
dat_SMCC=escalc(measure="SMCC",data=fMRS,ni=n,m1i=mean_s,m2i=mean_r,sd1i=s
d_s,sd2i=sd_r,ri=r
,append=TRUE)
author year n mean_r sd_r mean_s sd_s r yi vi
1 Tom 2006 9 0 0 0.12 0.03 0 3.6108 0.8354
2 Jack 2012 6 0 0 0.23 0.05 0 3.8674 1.4131
3 Zhu 2013 8 0 0 0.18 0.05 0 3.1975 0.7640
Sincerely
--
Mario Petretta
Department of Translational Medical Sciences
Naples University Federico II
Italy