| pvar {plm} | R Documentation |
This function checks for each variable of a panel if it has an individual and a time variation.
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)