Example 6

Stratified Poisson Regression.

A study investigated whether the number of nasal cancer deaths among workers in a nickel factory in Wales is related to exposure to gaseous compounds while manufacturing nickel alloys. The dataset consists of 72 records representing 15,194 observations.

Variables: AFE: Age first employed; YFE: Year first employed; TFE: Time since first employed; NCDEATHS: Number of nasal cancer deaths)

Notice that the asymptotic method computations did not converge. The Exact method results indicate that both the covariates YFE and TFE are highly significant.

Reference:
Breslow, NE & Day , NE (1987). Statistical Methods in Cancer Research. Int.Agency for Research on Cancer, Lyon.