metareg: Meta-regression

Description

Meta-regression for objects of class meta. This is a wrapper function for the R function rma.uni in the R package metafor (Viechtbauer 2010).

Usage

metareg(x, formula, method.tau=x$method.tau, ...)

Arguments

An object of class meta.

formula

Either a character string or a formula object.

method.tau

A character string indicating which method is used to estimate the between-study variance tau-squared. Either "FE", "DL", "REML", "ML", "HS", "SJ", "HE"

...

Additional arguments (ignored at the moment).

Value

An object of class c("metareg", "rma.uni","rma"). Please look at the help page of R function rma.uni for more details on the output from this function.
In addition, a list .meta is added to the output containing the following components:
x, formula, method.tauAs definied above.
callFunction call.
versionVersion of R package meta used to create object.
version.metaforVersion of R package metafor used to create object.

Details

This R function is a wrapper function for R function rma.uni in the R package metafor (Viechtbauer 2010), i.e. the function metareg can only be used if the R package metafor is installed.

References

Viechtbauer W (2010), Conducting Meta-Analyses in R with the Metafor Package. Journal of Statistical Software, 36, 1--48.

Examples

Run this code

data(Fleiss93cont)

# Add some (fictious) grouping variables:
Fleiss93cont$age <- c(55, 65, 55, 65, 55)
Fleiss93cont$region <- c("Europe", "Europe", "Asia", "Asia", "Europe")

meta1 <- metacont(n.e, mean.e, sd.e,
                  n.c, mean.c, sd.c,
                  data=Fleiss93cont, sm="MD")


mu1 <- update(meta1, byvar=region)

mu2 <- update(meta1, byvar=region,
              tau.common=TRUE, comb.fixed=FALSE)

# Warnings due to wrong ordering of arguments (order has changed with
# version 3.0-0 of R package meta)
#
metareg(~region, meta1)
metareg(~region, data=meta1)

# Warning as no information on covariate is available
#
metareg(meta1)

# Do meta-regression for covariate region
# (see R code to create object mu2)
#
metareg(mu2)

# Same result for
# - tau-squared
# - test of heterogeneity
# - test for subgroup differences
# (as argument 'tau.common' was used to create mu2)
#
mu2
metareg(mu2)
metareg(meta1, region)
#
# Different result for
# - tau-squared
# - test of heterogeneity
# - test for subgroup differences
# (as argument 'tau.common' is - by default - FALSE)
#
mu1

# Generate bubble plot
#
bubble(metareg(mu2))

# Do meta-regression with two covariates
#
metareg(mu1, region + age)

# Do same meta-regressions using 'official' formula notation
#
metareg(meta1, ~region)
metareg(mu1, ~region + age)

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