pdim {plm} | R Documentation |
This function checks the number of individuals and time observations in the panel and whether it is balanced or not.
pdim(x,...) ## S3 method for class 'data.frame': pdim(x, index = NULL, ...) ## S3 method for class 'panelmodel': pdim(x, ...) ## S3 method for class 'pdata.frame': pdim(x, ...)
x |
a data.frame , a pdata.frame or a panelmodel object, |
index |
see pdata.frame , |
... |
further arguments. |
pdim
is called by the estimation functions.
An object of class pdim
containing the following elements:
nT |
a list containing n , the number of individuals, T , the number of time observations, N the total number of observations, |
TinT |
a list containing two vectors : Ti gives the
number of observations for each individuals and nt gives
the number of individuals observed for each period, |
balanced |
a logical value : TRUE for a balanced panel, FALSE for an unbalanced panel, |
panel.names |
a list of character vectors : id.names
contains the names of each individual and time.names
contains the names of each period. |
Yves Croissant
# There are 595 individuals data("Wages", package = "plm") pdim(Wages, 595) # Gasoline contains two variables which are individual and time indexes # and are the first two variables data("Gasoline", package="plm") pdim(Gasoline) # Hedonic is an unbalanced panel, townid is the individual index data("Hedonic", package = "plm") pdim(Hedonic, "townid") # An example of the panelmodel method data("Produc", package = "plm") z <- plm(log(gsp)~log(pcap)+log(pc)+log(emp)+unemp,data=Produc, model="random", subset = gsp > 5000) pdim(z)