The general Poisson regression model
was used to describe the
joint effects of each of the explanatory variables of interest on
cause-specific mortality. Maximum likelihood estimates of the
parameters and LRT statistics were obtained using widely available
software [4,11]. The baseline rate 
represents the
age-specific death rate for individuals at the reference level of each
of the explanatory variables. In previous reports on the X-10 only
subcohort [15,16] a parametric model was used to describe the
baseline rates, i.e.
where 
= age at interval mid-point. In this report we will
use the external/internal model ([1], Chapter 4)
in which the baseline rates are assumed to be proportional to the
known external standard rates 
(U. S. white male
rates) was used. To contrast and further explain these two models
both of them were used to summarize the data for the seven dimensional
table of observed and expected deaths for all cancers for the
X-10/Y-12 ever sub-cohort.
