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

[petretta at unina.it]

Many thanks to Wolfgang Wiechtbauer for the explanation.

Sincerely

Mario Petretta


Message: 31
  Date: Thu, 21 Nov 2013 19:08:14 +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:
          <077E31A57DA26E46AB0D493C9966AC730D99255ED7 a UM-MAIL4112.unimaas.nl>
  Content-Type: text/plain; charset="us-ascii"

  .cmicalc is a non-exported function. You can see the code with:

  getAnywhere(.cmicalc)

  Best,
  Wolfgang


[Nascondi Testo quotato]
-----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: Thursday, November 21, 2013 13:39
  To: r-help a 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 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

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-- 
Mario Petretta
Department of Translational Medical Sciences
Naples University Federico II
Italy