Table 1. Summary statistics comparing goodness of fit for different COPD mortality maximum likelihood models.

Model	Degree of freedom	Deviance	p Value*
Age	36	4933.8
Age period (AP)	32	1769.9	<0.001
Age cohort (AC)	24	69.3	<0.001
Age-period-cohort (APC)	21	43.9

*p Values are based on the Chi square test for comparisons between AP and AC model with the full APC model.