[R] metafor

[Chuck Cleland]

On 7/24/2009 11:40 AM, Frank Pearson wrote:
> I had found the author's (Wolfgang Viechtbauer) earlier meta-analytic code in R, MiMa, useful. so I have been exploring metafor using an example dataset from MiMa.  metafor provides a lot more.  However, MiMa provided parameter estimates, standard errors, z values, etc. for individual moderators in the meta-analysis, but I don't see how to obtain these from metafor.  Have you any help about how to get this?
>  
> Frank 

Hi Frank:
  Which function in the metafor package are you using to fit the
meta-regression model?  The following works for me to reproduce one of
the analyses in the MiMa Tutorial
(http://www.wvbauer.com/downloads/mima_tutorial.pdf):

library(metafor)

f <- "STUDY N1 N2 YI VI MINUTES TRAINED MEANAGE
1 30 30 0.444 0.068 30 0 28
2 46 39 -0.495 0.049 10 0 42
3 15 15 0.195 0.134 20 1 31
4 10 10 0.546 0.207 40 1 39
5 12 12 0.840 0.181 20 1 17
6 10 10 0.105 0.200 30 1 51
7 26 24 0.472 0.082 15 1 26
8 18 14 -0.205 0.128 10 0 64
9 12 12 1.284 0.201 45 1 48
10 12 12 0.068 0.167 30 1 40
11 15 15 0.234 0.134 30 1 52
12 12 12 0.811 0.180 30 1 33
13 15 15 0.204 0.134 30 1 20
14 18 18 1.271 0.134 60 1 27
15 15 15 1.090 0.153 45 1 52
16 43 35 -0.059 0.052 10 1 61"

madf <- read.table(textConnection(f), sep=" ", header=TRUE)

rma(YI, VI, mods=cbind(MINUTES, TRAINED, MEANAGE), data=madf)

Mixed-Effects Model (k = 16; tau^2 estimator: REML)

tau^2 (estimate of residual amount of heterogeneity): 0 (SE = 0.0472)
tau (sqrt of the estimate of residual heterogeneity): 0

Test for Residual Heterogeneity:

QE(df = 12) = 9.1238, p-val = 0.6923

Test of Moderators (coefficient(s) 2,3,4):

QM(df = 3) = 28.8348, p-val = 0

Model Results:

         estimate      se     zval    pval    ci.lb   ci.ub
intrcpt   -0.2956  0.3488  -0.8473  0.3968  -0.9792  0.3881
MINUTES    0.0250  0.0067   3.7149  0.0002   0.0118  0.0381  ***
TRAINED    0.3011  0.1953   1.5415  0.1232  -0.0817  0.6839
MEANAGE   -0.0060  0.0063  -0.9518  0.3412  -0.0182  0.0063

---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

> sessionInfo()

R version 2.9.1 (2009-06-26)
i386-pc-mingw32

locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
States.1252;LC_MONETARY=English_United
States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] metafor_0.5-0

hope this helps,

Chuck

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-- 
Chuck Cleland, Ph.D.
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