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)