[R] metafor escalc(measure="SMCC")
petretta at unina.it
petretta at unina.it
Tue Nov 19 11:29:25 CET 2013
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=sd_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
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