pvar {plm} | R Documentation |
This function checks for each variable of a panel if it varies cross-sectionally and over time.
pvar(x, ...) ## S3 method for class 'data.frame': pvar(x, index = NULL, ...) ## S3 method for class 'pdata.frame': pvar(x, ...) ## S3 method for class 'pvar': print(x, ...)
x |
a data.frame , |
index |
see plm.data , |
... |
further arguments. |
pvar
can be time consuming for ``big'' panels.
An object of class pvar
containing the following elements:
id.var |
a logical vector with TRUE values if the
variable has individual variation, FALSE otherwise, |
time.var |
a logical vector with TRUE values if the
variable has time variation, FALSE otherwise, |
Yves Croissant
#There are 595 individuals data("Wages",package="plm") pvar(Wages, 595) # Gasoline contains two variables which are individual and time indexes # and are the first two variables data("Gasoline", package = "plm") pvar(Gasoline) # Hedonic is an unbalanced panel, townid is the individual index; # the drop.index argument is passed to pdata.frame data("Hedonic", package = "plm") pvar(Hedonic,"townid", drop.index = TRUE) # same using pdata.frame Hed <- pdata.frame(Hedonic, "townid", drop.index = TRUE) pvar(Hed)