Subsample of Observations from Panel Data

returns a subsample of a panel data set; in particular drops all observations that are not in keepids. If it is not set, randomly keeps nkeep observations.

subsample(dta, idname, tname, keepids = NULL, nkeep = NULL)

Arguments

dta: a data.frame which is a balanced panel
idname: the name of the id variable
tname: the name of the time variable
keepids: which ids to keep
nkeep: how many ids to keep (only used if keepids is not set); the default is the number of unique ids

Value

a data.frame that contains a subsample of dta

Examples

 if(!requireNamespace("plm")) {
  if(interactive() || is.na(Sys.getenv("_R_CHECK_PACKAGE_NAME_", NA))) {
    stop("package 'plm' is required for this example")
  } else q() }
data("LaborSupply", package="plm")
nrow(LaborSupply)
#> [1] 5320
unique(LaborSupply$year)
#>  [1] 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
ss <- subsample(LaborSupply, "id", "year", nkeep=100)
nrow(ss)
#> [1] 1000