Table 2. Twin Model Fit Statistics.
| Model | −2LLa | Parameters | df | Δχ2b | Δdfc | P valued |
|---|---|---|---|---|---|---|
| Paranoia | ||||||
| Full bivariate | 49 291.69 | 17 | 19 292 | NA | NA | NA |
| Drop A moderation | 49 293.00 | 16 | 19 293 | 1.32 | 1 | .25 |
| Drop C moderation | 49 291.70 | 16 | 19 293 | 0.01 | 1 | .91 |
| Drop E moderation | 49 292.59 | 16 | 19 293 | 0.90 | 1 | .34 |
| Drop all moderation | 49 299.02 | 14 | 19 295 | 7.33 | 3 | .06 |
| Hallucinations | ||||||
| Full bivariate | 49 578.99 | 17 | 19 302 | NA | NA | NA |
| Drop A moderation | 49 579.16 | 16 | 19 303 | 0.16 | 1 | .69 |
| Drop C moderation | 49 579.00 | 16 | 19 303 | 0.00 | 1 | .95 |
| Drop E moderation | 49 582.82 | 16 | 19 303 | 3.82 | 1 | .05 |
| Drop all moderation | 49 588.62 | 14 | 19 305 | 9.63 | 3 | .02 |
| Cognitive disorganization | ||||||
| Full bivariate | 49 476.53 | 17 | 19 291 | NA | NA | NA |
| Drop A moderation | 49 476.87 | 16 | 19 292 | 0.34 | 1 | .56 |
| Drop C moderation | 49 476.53 | 16 | 19 292 | 0.00 | 1 | <.99 |
| Drop E moderation | 49 488.19 | 16 | 19 292 | 11.66 | 1 | .001 |
| Drop all moderation | 49 494.14 | 14 | 19 294 | 17.61 | 3 | .001 |
| Grandiosity | ||||||
| Full bivariate | 49 509.94 | 17 | 19 246 | NA | NA | NA |
| Drop A moderation | 49 510.30 | 16 | 19 247 | 0.37 | 1 | .55 |
| Drop C moderation | 49 511.65 | 16 | 19 247 | 1.71 | 1 | .19 |
| Drop E moderation | 49 513.53 | 16 | 19 247 | 3.59 | 1 | .06 |
| Drop all moderation | 49 518.32 | 14 | 19 249 | 8.38 | 3 | .04 |
| Anhedonia | ||||||
| Full bivariate | 49 541.41 | 17 | 19 249 | NA | NA | NA |
| Drop A moderation | 49 541.43 | 16 | 19 250 | 0.01 | 1 | .92 |
| Drop C moderation | 49 541.53 | 16 | 19 250 | 0.11 | 1 | .74 |
| Drop E moderation | 49 548.50 | 16 | 19 250 | 7.09 | 1 | .008 |
| Drop all moderation | 49 553.57 | 14 | 19 252 | 12.16 | 3 | .007 |
| Negative symptoms | ||||||
| Full bivariate | 47 326.21 | 17 | 19 327 | NA | NA | NA |
| Drop A moderation | 47 326.96 | 16 | 19 328 | 0.75 | 1 | .39 |
| Drop C moderation | 47 326.21 | 16 | 19 328 | 0.00 | 1 | .99 |
| Drop E moderation | 47 326.65 | 16 | 19 328 | 0.44 | 1 | .51 |
| Drop all moderation | 47 332.04 | 14 | 19 330 | 5.83 | 3 | .12 |
| APSS | ||||||
| Full bivariate | 90 237.22 | 17 | 43 692 | NA | NA | NA |
| Drop A moderation | 90 237.77 | 16 | 43 693 | 0.55 | 1 | .46 |
| Drop C moderation | 90 237.65 | 16 | 43 693 | 0.43 | 1 | .51 |
| Drop E moderation | 90 244.17 | 16 | 43 693 | 6.95 | 1 | .008 |
| Drop all moderation | 90 258.61 | 14 | 43 695 | 21.39 | 3 | <.001 |
Abbreviation: NA, not applicable.
a
−2LL = fit statistic, −2 × log likelihood of the data.
b
Δχ2 = −2LL discrepancy between models, distributed χ2.
c
The difference in degrees of freedom between the 2 models is equivalent to the difference in number of parameters between 2 models.
d
Significant values indicate that a nested model fits statistically significantly more poorly than the model it is being compared to, supporting the statistical significance of the parameter(s) dropped from the model.