Displaying 20 results from an estimated 200 matches similar to: "Metafor"

2010 Jul 02

1

metafor and meta-analysis at arm-level

Hi,
I have been looking for an R package which allowed to do meta-analysis
(both pairwise and network/mixed-treatment) at arm-level rather than at
trial-level, the latter being the common way in which meta-analysis is
done.
By arm-level meta-analysis I mean one that accounts for data provided at
the level of the individual arms of each trial and that does not simply
derive the difference

2009 Dec 14

1

help: forest plots

Hi All,
I'm fitting a Poisson regression. And I want to plot 95% Confidence Interval
of Regression Estimates.
After coming back to original scale (using following formula):
exponential(estimate +/- 1.96*SE),
at best I can get the output in the form of estimates, lower_limit,
upper_limit values.
As far I know forest() in metafor package needs input in the form of
estimates and their

2010 Jan 26

1

add points to 3D plot using p3d {onion}

Hi,
Can anyone guide me as to how I can add points to a p3d() plot from
the onion package?? I want to plot points with different colors on the
same 3D plot.? Perhaps I can do this without adding points but somehow
directing the 'h' parameter to give different color to points based on
a factor I assign to them?
FYI, I can do this using using scatterplot3d() and points3d(), but
these plots

2009 Nov 08

3

MCMC gradually slows down

Hello,
I have written a simple Metropolis-Hastings MCMC algorithm for a
binomial parameter:
MHastings = function(n,p0,d){
theta = c()
theta[1] = p0
t =1
while(t<=n){
phi = log(theta[t]/(1-theta[t]))
phisim = phi + rnorm(1,0,d)
thetasim = exp(phisim)/(1+exp(phisim))
r = (thetasim)^4*(1-thetasim)^8/(theta[t]^4*(1-theta[t])^8)
if(runif(1,0,1)<r){
theta[t+1] =

2010 Jan 31

2

lmer, mcmcsamp, coda, HPDinterval

Hi,
I've got a linear mixed model created using lmer:
A6mlm <- lmer(Score ~ division + (1|school), data=Age6m)
(To those of you to whom this model looks familiar, thanks for your patience
with this & my other questions.) Anyway, I was trying this to look at the
significance of my fixed effects:
A6post <- mcmcsamp(A6mlm, 50000)
library(coda)
HPDinterval(A6post)
..but I got this

2009 Jul 24

1

metafor

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

2011 Oct 03

1

Meta-analysis of test statistics in "metafor" package?

Hi -
I am conducting a meta-analysis and I have a matrix of f-statistics, Ns and
dfs from a series of studies that tested for an interaction in a 2x2 anova.
I'd like to test whether the 2x2 interaction is significant in the
aggregate.
Similarly, I have a matrix of chi-square statistics that I'd like to
meta-analyze.
How can I input these test statistics into the "metafor"

2010 Nov 11

1

metafor: including phylogenetic non-independence among species?

Hello, Is it possible to include information about phylogenetic relatedness
among species (when species are replicates for each study within a
meta-analysis) in a meta-anlaysis in the metafor package?
Alternatively, I wonder if the method f Lajeunesse 2009 American Naturalist
has been adopted in R in any fashion?
Thanks, Scott Chamberlain
[[alternative HTML version deleted]]

2012 Jan 14

1

metafor: weights computation in Mantel-Haenszel method

Dear R users,
In metafor 1.6-0, the Mantel-Haenszel method is implemented by the rma.mh() function. I have observed that the sum of the weights computed by weights(x) doesn't add to 100% when x is an object of class rma.mh. The consequences of this fact can be clearly seen when a forest diagram is drawn with forest(x), which calls weights(x) (or more precisely, the method weights.rma.mh()

2009 Aug 13

1

metafor random effects meta-analysis

Hello,
Great to see the new metafor package for meta-analysis.
I would like to perform a meta-analysis in which I initially calculate the intercept of the model with a nested random-effects structure. In lme, this would be
model<- lme(v3~1, random=~1|species/study, weights = varFixed(~Wt), method = "REML")
where multiple effects sizes are measured for some studies and more

2010 Dec 20

1

Metafor package

I have some question about metafor package.
I'm interest to perform a random effect meta-analysis of proportion
(single group summary of prevalence of disease in a population as
reported by different study)
It ask:
1. "PFT": The Freeman-Tukey double arcsine transformed proportion is
reported to be equal to 1/2*(asin(sqrt(xi/(ni+1))) +
asin(sqrt((xi+1)/(ni+1)))).

2007 Apr 03

1

Calculating DIC from MCMC output

Greetings all,
I'm a newcomer to Bayesian stats, and I'm trying to calculate the
Deviance Information Criterion "by hand" from some MCMC output.
However, having consulted several sources, I am left confused as to
the exact terms to use. The most common formula can be written as
DIC = 2*Mean(Deviance over the whole sampled posterior distribution)
- Deviance(Mean

2011 Jan 12

1

metafor/ meta-regression

Hi I have tryed to do the meta-regression in metafor package, but I
would like to get the standardized coefficients for each variable, however in
command:
Ø res<-rma.uni (yi, vi,
method="REML", mods=~cota+DL+uso+gadiente+idade, data= turbidez)
I just have the coefficients no standardized (estimate) of the multiple
regression.
What I need to do?
Thanks
Fernanda Melo

2012 Sep 27

1

What to use for ti in back-transforming summary statistics from F-T double square-root transformation in 'metafor'

Hi Dr. Viechtbauer,
I'm doing meta-analysis using your package 'metafor'. I used the 'IRFT' to transform the incident rate. But when I tried to back-transform the summary estimates from function rma, I don't know what's the appropriate ti to feed in function transf.iirft. I searched and found your post about using harmonic mean for ni to back-transform the double

2013 Dec 12

1

refline in forest() {metafor}

Hello all,
I am using forest.rma to plot a random effects model meta-analysis. I noticed
that refline sets a vertical line indicating the null hypothesis.
Is there a way to draw another vertical line, possibly dashed, centered on the
summary estimate?
Prof. Viechtbauer, if you happen to read this, I'd like to thank you for making
an excellent package. I have been using the metafor package

2013 Mar 02

1

Metafor "SMCR" Pre-Post Effect sizes

Dear all,
I am very grateful that Wolfgang Viechtbauer implemented the standardised mean change for dependent
groups. I was playing around a bit today, and I am not sure if I understand the "SMCR" procedure correctly. The documentation states that sd1i and sd2i are needed, but it seems to me that SMCR is ignoring sd2i (so Variances are not pooled). Instead, it uses sd1i (pre-test sd),

2011 Aug 05

1

Main-effect of categorical variables in meta-analysis (metafor)

Dear R-experts!
In a meta-analysis (metafor) I would like to assess the effect of two
categorical covariates (A & B) whereas they both have 4 levels.
Is my understanding correct that this would require to dummy-code (0,1) each
level of each covariate (A & B)?
However I am interested in the main-effects and the interaction of these two
covariates and the dummy-coding would only allow to

2012 Dec 31

2

a problem for metafor package

Dear sir or madam
I want to know how to use "metafor"package do a meta anlysis, forest plot show the results of whole study and results of two subgroups
like this the forest plot show in the attachment.
looking forword to your reply
Regards and Cheers
Xudong Liu
School of Public Health and Primary Care
The Chinese University of Hong Kong
Email: liuxudong at cuhk.edu.hk

2012 Jul 24

1

Annotate forest plot 'forest.rma()' for meta-analysis with metafor package

Dear R-experts,
The forest.rma() function from the metafor package creates nice forest
plots for presenting the results of a meta-analysis. These plots can be
annotated for e.g. giving names to the columns. E.g. as in the
documentation of the package:
data(dat.bcg)
### meta-analysis of the log relative risks using a random-effects model
res <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg,

2011 Aug 17

3

questions about "metafor" package

Hello,
I would like to do a meta-analysis with the package « metafor ». Ideally I would like to use a mixed model because I’m interested to see the effect of some moderators. But the data set I managed to collect from literature presents two limits.
- Firstly, for each observation, I have means for a treatment and for a control, but I don’t always have corresponding standard