total number of observations : 4165
observation : individuals
country : United States
data(Wages)"male" and "female"Baltagi, Badi H. (2013) Econometric Analysis of Panel Data, 5th ed., John Wiley and Sons.
Cornwell, C. and P. Rupert (1988) Efficient estimation with panel data: an empirical comparison of instrumental variables estimators, Journal of Applied Econometrics, 3, pp. 149--155.