Table 1.
Results of model fitting for number of lifetime gambling episodes using twin and sibling pairs
| Sex effects |
||||||
|---|---|---|---|---|---|---|
| Model | Description | Qualitative | Quantitative | Δ χ 2 | Δdf | ΔAIC |
| Ia | ACET | + | + | – | – | – |
| II | ACET | + | – | + 3.369 | +3 | –2.631 |
| III | ACET | – | – | + 3.369 | +5 | –6.631 |
| IVb | ACE | – | – | + 3.900 | +6 | –8.100 |
| V | CE | – | – | + 19.330 | +7 | + 5.330 |
| VI | AE | – | – | + 28.362 | +7 | + 14.362 |
A, Additive genetic effects; C, shared environment; E, individual-specific environment; T, special twin environment; df, degrees of freedom; AIC, Akaike's Information Criterion.
a
–2 log likelihood = 4615.856, df = 1736, AIC = 1143.856.
b
Best-fit model.