[R] metafor escalc(measure="SMCC")

[petretta at unina.it]

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 a maastrichtuniversity.nl>
To: "petretta a unina.it" <petretta a unina.it>, "r-help a r-project.org"
        <r-help a r-project.org>
Subject: Re: [R] metafor escalc(measure="SMCC")
Message-ID:
        <077E31A57DA26E46AB0D493C9966AC730D9925568A a 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 a r-project.org [mailto:r-help-bounces a r-project.org]
> On Behalf Of petretta a unina.it
> Sent: Tuesday, November 19, 2013 11:29
> To: r-help a 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)
> > dat_SMCC
> 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
>