| addvar {meta} | R Documentation |
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.
## 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)
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 |
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.
Guido Schwarzer sc@imbi.uni-freiburg.de
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)