plm (version 0.3-1)

pdim: Check for the Dimensions of the Panel

Description

This function checks the number of individuals and time observations in the panel and whether it is balanced or not.

Usage

pdim(x,...)
## S3 method for class 'data.frame':
pdim(x, indexes = NULL, ...)

Arguments

x

a "data.frame" or a "plm" object,

indexes

see plm.data,

...

further arguments.

Value

• 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.

Details

pdim is called by the estimation functions.

See Also

plm.data

Examples

#There are 595 individuals

data("Wages", package="Ecdat")
pdim(Wages, 595)

# Gasoline contains two variables which are individual and time indexes
# and are the first two variables
data("Gasoline", package="Ecdat")
pdim(Gasoline)

# Hedonic is an unbalanced panel, townid is the individual index
data("Hedonic", package="Ecdat")
pdim(Hedonic, "townid")