Table 3.

Akaike Information Criteria (AIC) for Weibull models with explanatory variables of gender and birth cohort (1980–1984 and 1985–1994) for patients enrolled on the US Cystic Fibrosis Foundation Patient Registry surviving their first birthday

Model	Explanatory variable(s)	Weibull model AIC
A	Null (no variables)	24 302.8
B	Gender	24 232.1
C	Birth cohort	24 128.7
D	Gender and birth cohort as main effects	24 060.3
E	Gender and birth cohort with interaction	24 062.2
F	Separated models for gender	24 232.4
	Male	10 828.4
	Female	13 404.0
G	Separated models for birth cohort	24 108.3
	1980–1984	13 000.1
	1985–1994	11 108.2