Table 2.
Comparison of AIC of various models. Models were compared in a predetermined stepwise fashion based on biological significance and increasing complexity of the variables. Models with lower AIC are considered better fitting. Best fitting model in italics.
| Model | Variables included in the model | AIC |
|---|---|---|
| 1 | Intercept and random effects for animal and year (null model) | 7415 |
| 2 | Rearing, sex, age, and random effects for animal and year (covariate only model) | 7064 |
| 3 | Rearing, sex, age, origin and random effects for animal and year | 7061 |
| 4 | Rearing, sex, age, origin, response to novel object, and random effects for animal and year |
7027 |
| 5 | Rearing, sex, age, origin, response to novel object, enrichment device, and random effects for animal and year |
7024 |
| 6 |
Rearing, sex, age, origin, response to novel object, enrichment device, pairing,
and random effects for animal and year |
6985 |