plm (version 2.6-3)

ranef.plm: Extract the Random Effects

Description

Function to calculate the random effects from a plm object (random effects model).

Usage

# S3 method for plm
ranef(object, effect = NULL, ...)

Value

A named numeric with the random effects per dimension (individual or time).

Arguments

object

an object of class "plm", needs to be a fitted random effects model,

effect

NULL, "individual", or "time", the effects to be extracted, see Details,

...

further arguments (currently not used).

Author

Kevin Tappe

Details

Function ranef calculates the random effects of a fitted random effects model. For one-way models, the effects of the estimated model are extracted (either individual or time effects). For two-way models, extracting the individual effects is the default (both, argument effect = NULL and effect = "individual" will give individual effects). Time effects can be extracted by setting effect = "time".

Not all random effect model types are supported (yet?).

See Also

fixef() to extract the fixed effects from a fixed effects model (within model).

Examples

data("Grunfeld", package = "plm")
m1 <- plm(inv ~ value + capital, data = Grunfeld, model = "random")
ranef(m1) # individual random effects

# compare to random effects by ML estimation via lme from package nlme
library(nlme)
m2 <- lme(inv ~ value + capital, random = ~1|firm, data = Grunfeld)
cbind("plm" = ranef(m1), "lme" = unname(ranef(m2)))

# two-ways RE model, calculate individual and time random effects
data("Cigar", package = "plm")
tw <- plm(sales ~ pop + price, data = Cigar, model = "random", effect = "twoways")
ranef(tw)                   # individual random effects
ranef(tw, effect = "time")  # time random effects