Table 3.
Fit statistics and parameter estimates for best fitting univariate models: psychotic experiences and cannabis use.
| Model | Model fit |
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Compared to saturated model |
Compared to ACE model |
Univariate parameter estimates |
||||||||||||
| −2LL | d.f. | LRT | Δd.f. | AIC | p | LRT | Δd.f. | AIC | p | A (CI) | C (CI) | E (CI) | ||
| Paranoia | Sat | 22,662.50 | 6515 | – | – | – | – | – | – | – | – | – | ||
| ACE | 22,678.88 | 6530 | 16.38 | 15 | −13.62 | 0.36 | – | – | – | 0.46 (0.34,0.57) | 0.08 (0.01,0.18) | 0.46 (0.43,0.50) | ||
| CE | 22,734.61 | 6531 | 72.11 | 16 | 40.11 | <0.01 | 55.73 | 1 | 53.73 | <0.01 | – | – | – | |
| AEa | 22,680.95 | 6531 | 18.45 | 16 | −13.55 | 0.30 | 2.07 | 1 | 0.07 | 0.15 | 0.54 (0.51,0.58) | – | 0.46 (0.42,0.49) | |
| Hallucinations | Sat | 22,312.35 | 6525 | – | – | – | – | – | – | – | ||||
| ACEa | 22,326.96 | 6540 | 14.60 | 15 | −15.40 | 0.48 | – | – | – | 0.27 (0.14,0.39) | 0.20 (0.10,0.31) | 0.53 (0.49,0.57) | ||
| CE | 22,344.02 | 6541 | 31.67 | 16 | −0.33 | 0.01 | 17.06 | 1 | 15.06 | <0.01 | – | – | – | |
| AE | 22,340.18 | 6541 | 27.83 | 16 | −4.17 | 0.03 | 13.22 | 1 | 11.22 | <0.01 | – | – | – | |
| Cognitive disorganization | Sat | 22,190.41 | 6516 | – | – | – | – | – | – | – | – | – | ||
| ACEa | 22,210.01 | 6531 | 19.61 | 15 | −10.39 | 0.19 | – | – | – | 0.39 (0.27,0.52) | 0.11 (0.01,0.21) | 0.50 (0.46,0.54) | ||
| CE | 22,248.08 | 6532 | 57.67 | 16 | 25.67 | <0.01 | 38.07 | 1 | 36.07 | <0.01 | – | – | – | |
| AE | 22,214.01 | 6532 | 23.61 | 16 | −8.39 | 0.10 | 4.00 | 1 | 2.00 | 0.05 | – | – | – | |
| Parent-rated negative symptoms | Sat | 17,703.14 | 6528 | – | – | – | – | – | – | – | – | – | ||
| ACEa | 17,710.15 | 6540 | 7.00 | 12 | −15.00 | 0.86 | – | – | – | 0.46 (0.39,0.54) | 0.42 (0.34,0.48) | 0.12 (0.11,0.13) | ||
| CE | 17,934.96 | 6541 | 231.81 | 13 | 205.81 | <0.01 | 224.81 | 1 | 222.81 | <0.01 | – | – | – | |
| AE | 17,801.98 | 6541 | 98.84 | 13 | 72.84 | <0.01 | 91.83 | 1 | 89.83 | <0.01 | – | – | – | |
| Cannabis | Sat | 2516.56 | 4891 | – | – | – | – | – | – | – | – | – | – | – |
| ACEa | 2521.56 | 4894 | 5.01 | 3 | −0.99 | 0.17 | – | – | – | 0.37 (0.20,0.57) | 0.55 (0.36,0.70) | 0.08 (0.05,0.12) | ||
| CE | 2541.385 | 4895 | 24.83 | 4 | 16.83 | <0.01 | 19.82 | 1 | 17.82 | <0.01 | – | – | – | |
| AE | 2547.885 | 4895 | 31.32 | 4 | 23.32 | <0.01 | 26.32 | 1 | 24.32 | <0.01 | – | – | – | |
Note: additive genetic influences (A), common environmental influences (C), and unique environmental influences (E) shown in the right hand column of the table for each scale. Sat=saturated model; ACE=full model testing genetic, common and unique environmental influences; AE=model testing genetic and unique environment influences; CE=model testing common and unique environmental influences; −2LL=negative 2 log likelihood; d.f.=degrees of freedom; LRT=likelihood ratio chi-square test comparing the −2LL fit of each model to the −2LL fit of the saturated model; Δd.f.=difference in degrees of freedom comparing each model to the saturated model; AIC=Akaike׳s Information Criterion (lower values reflect a better fit); p=p-value. A=additive genetic influences, C=common environmental influences, E=Unique environmental influences.
Best fitting model. 95% Confidence intervals in parentheses.