Table 4.

Comparison of age–period–cohort models for lung cancer incidences with Poisson regression in Sihui

Model	DF	Males		Females
		Dev	P valuea	Dev	P valuea
Age	40	244.5	<0.001	187.3	<0.001
Age–period	36	56.7	0.008	56.6	0.048
Age–cohort	27	42.3	0.047	50.3	0.009
Age–period–cohort	24	29.8	0.252	24.1	0.562
Period curvature effectb	3	12.5	0.007	26.2	<0.001
Cohort curvature effectb	12	26.9	0.003	32.5	0.002

DF degree of freedom, Dev deviance.

^a P value was from a Chi square test of the goodness-of-fit of the model.

^bEffects were assessed by comparing the age–period–cohort model with the age-cohort model (period curvature effect) and the age–period–cohort model with the age-period model (cohort curvature effect).