Fertility and Contraception
Robey data frame has 50 rows and 3 columns.
The observations are developing nations around 1990.
Robey, B., Shea, M. A., Rutstein, O. and Morris, L. (1992) The reproductive revolution: New survey findings. Population Reports. Technical Report M-11.
Fox, J. (1997) Applied Regression, Linear Models, and Related Methods. Sage.