/* Use McCullagh and Nelder 1989 data on ship accidents */

use http://www.stata-press.com/data/r9/ships

/* Specify random-effects Poisson model of whether the incident rate is affected by */
/* the time period in which the ship was constructed and operated. The measure of exposure */
/* is the months of service for the ship. */

xtpoisson accident op_75_79 co_65_69 co_70_79, i(ship) ex(service) irr

/* If we want to fix a fixed effects specification instead of a random effects... */

xtpoisson accident op_75_79 co_65_69 co_70_79, i(ship) ex(service) irr fe