metafor escalc(measure="SMCC")

-----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)

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