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Last data update: 2014.03.03

R: Check for the Dimensions of the Panel

pdim	R Documentation

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, index = NULL, ...)
## S3 method for class 'panelmodel'
pdim(x, ...)
## S3 method for class 'pdata.frame'
pdim(x, ...)

Arguments

`x`	a `data.frame`, a `pdata.frame` or a `panelmodel` object,
`index`	see `pdata.frame`,
`...`	further arguments.

Details

pdim is called by the estimation functions.

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.

Author(s)

Yves Croissant

Examples


# 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)