transf {metafor} | R Documentation |
A set of transformation functions useful for meta-analyses.
transf.rtoz(x, ...) transf.ztor(x, ...) transf.logit(x, ...) transf.ilogit(x, ...) transf.ztor.int(x, targs, ...) transf.exp.int(x, targs, ...)
x |
a vector of values to be transformed. |
targs |
a list with additional arguments for the transformation function. See ‘Details’. |
... |
other arguments. |
The following transformation functions are currently implemented:
transf.rtoz
: Fisher's r-to-z transformation.
transf.ztor
: inverse of the Fisher's r-to-z transformation.
transf.logit
: logit (log odds) transformation.
transf.ilogit
: inverse of the logit transformation.
transf.ztor.int
: integral transformation method for the z-to-r transformation.
transf.exp.int
: integral transformation method for the exponential transformation.
The integral transformation method for a transformation function h(z) integrates h(z) x f(z) over the limits targs$lower
and targs$upper
, where f(z) is the density of a normal distribution with mean equal to x
and variance equal to targs$tau2
.
A vector with the transformed values.
Wolfgang Viechtbauer; wvb@www.wvbauer.com; http://www.wvbauer.com/
### load BCG vaccine data data(dat.bcg) ### meta-analysis of the log risk ratios using a random-effects model res <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg, measure="RR", data=dat.bcg, method="REML") ### average risk ratio with 95% CI predict(res, transf=exp) ### average risk ratio with 95% CI using integral transformation predict(res, transf=transf.exp.int, targs=list(tau2=res$tau2, lower=-4, upper=4))