library(plm)
data("Grunfeld", package = "plm")
ols <- plm(inv ~ value + capital, Grunfeld, model = "pooling")
ols2 <- plm(inv ~ value + lag(capital), Grunfeld, model = "pooling")
ols3 <- plm(inv ~ value + capital + lag(capital), Grunfeld, model = "pooling")
ols4 <- plm(inv ~ value + capital + lag(capital) + lag(capital,k = 2), Grunfeld, model = "pooling")