Nested mixed models showing effects of added parameters to model fit, North Carolina asbestos textile plants
| Model effects | AIC | −2 Log likelihood | Likelihood ratio test p value |
| Intercept only | 13594 | 13590 | |
| Year | 11539 | 11533 | <0.001 |
| Year, splines | 11184 | 11171 | <0.001 |
| Year, splines, plant | 11107 | 11089 | <0.001 |
| Year, splines zone (plant) | 10385 | 10303 | <0.001 |
| Year, splines, UJC (zone, plant) | 10270 | 10132 | <0.001 |
AIC, Akaike’s information criterion.