addvar {meta}R Documentation

Additional functions for objects of class meta

Description

The as.data.frame method returns a data frame containing information on individual studies, e.g., estimated treatment effect and its standard error. The function addvar can be used to add a single variable to an object of class meta which for example is useful to conduct sub-group analysis or meta-regression.

Usage

## S3 method for class 'meta':
as.data.frame(x, row.names=NULL, optional=FALSE, ...)

addvar(x, y, varname, by.x="studlab", by.y=by.x)

Arguments

x An object of class meta.
row.names NULL or a character vector giving the row names for the data frame.
optional logical. If TRUE, setting row names and converting column names (to syntactic names) is optional.
y A data frame with an additional covariate
varname A character specifying name of additional variable
by.x, by.y Specifications of the common columns (see merge)
... other arguments

Value

A data frame is returned by the function as.data.frame.
A single covariate is returned by the function addvar which can be added to an object of class meta. Internally, the merge function is utilised.

Author(s)

Guido Schwarzer sc@imbi.uni-freiburg.de

See Also

metabin, metacont, metagen

Examples

data(Fleiss93cont)
meta1 <- metacont(n.e, mean.e, sd.e, n.c, mean.c, sd.c, study,
                  data=Fleiss93cont, sm="SMD")
#
# Generate additional variable
#
Fleiss93cont$group <- c(1,2,1,1,2)
#
# Generate new variable by merging
# object 'meta1' and data frame 'Fleiss93cont'
#
meta1$group <- addvar(meta1, Fleiss93cont, "group", by.y="study")
as.data.frame(meta1)
summary(meta1, byvar=group)

[Package meta version 0.9-18 Index]