Suppose that the model contains parameters and that observations are used in model fitting. The fit criteria displayed by the LIFEREG procedure are calculated as follows:

• 2 log likelihood:

  where L is the maximized likelihood for the model.

• Akaike information criterion:

• corrected Akaike information criterion:

• Bayesian information criterion:

Refer to Akaike (1981, 1979) for details of AIC and BIC. Refer to Simonoff (2003) for a discussion of using AIC, AICC, and BIC in statistical modeling.