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Table 4 Twin-model fit statistics and parameter estimates

From: A longitudinal twin study of the association between childhood autistic traits and psychotic experiences in adolescence

  Comparative fit with saturated model Comparative fit with full ACE Cholesky
Model −2LL df Par. BIC Δχ 2 Δdf p AIC Δχ 2 Δdf p AIC
Autistic traits and anhedonia (five-variable decompositions)
Saturated 63,287.21 27,375 260 −158948.70
ACE sex diff. 63,489.32 27,535 100 −160045.50 202.11 160 <.05 −117.89
ACE const. a 63,619.71 27,580 55 −160280.40 332.50 205 <.001 −77.50 130.39 45 <.001 40.39
AE const. 63,784.42 27,595 40 −160237.50 497.20 220 <.001 57.20 164.71 15 <.001 134.71
CE const. 64,974.16 27,595 40 −159047.80 1686.94 220 <.001 1246.94 1345.45 15 <.001 1324.45
E const. 71,621.98 27,610 25 −152521.80 8334.77 235 <.001 7864.77 8002.27 30 <.001 7942.27
Autistic traits and parent-rated negative symptoms (five-variable decompositions)
Saturated 60,014.32 27,393 260 −162367.70
ACE sex diff. 60,189.54 27,553 100 −163491.40 175.22 160 .19 −144.78
ACE const. a 60,319.68 27,598 55 −163726.60 305.35 205 <.001 −104.65 130.13 45 <.001 40.13
AE 60,542.65 27,613 40 −163625.40 528.33 220 <.001 −7.02 222.98 15 <.001 192.98
CE 61,994.75 27,613 40 −162173.31 1980.42 220 <.001 1540.42 1675.07 15 <.001 1645.07
E 70,414.98 27,628 25 −153874.80 10400.66 235 <.001 9930.66 10095.31 30 <.001 10035.31
Parameter estimates from best-fitting decompositions
  Autistic traits age 8 Autistic traits age 12 Autistic traits age 14 Autistic traits age 16 Variance specific to psychotic experiences
  A1 C1 E1 A2 C2 E2 A3 C3 E3 A4 C4 E4 A5 C5 E5
Anhedonia .02 (.00/.05) .01 (.00/.05) .00 (−.01/.01) .00 (.00/.03) .01 (.00/.04) .00 (−.01/.01) .02 (.00/.05) .01 (.00/.04) .00 (.00/.01) .01 (.00/.05) .00 (−.01/.03) .02 (.00/.03) .32 (.26/.36) .00 (−.05/.06) .58 (.55/.61)
Total .03 .01 .03 .03 .90
Neg sym .02 (.00/.04) .10 (.04/.22) .00 (.00/.01) .01 (.00/.03) .06 (.01/.17) .00 (.00/.01) .05 (.03/.10) .00 (−.01/.01) .01 (.00/.01) .04 (.01/.07) .00 (−.02/.02) .02 (.01/.03) .45 (.40/.50) .10 (−.18/.18) .14 (.13/.15)
Total .12 .07 .06 .06 .69
  1. AE, CE, and E models are submodels within the ACE model that fit best. A1–A4, C1–C4, and E1–E4 are the paths shown in red in Fig. 1, and represent the influence of genetic and environmental causes of autistic traits on psychotic experiences, A5, C5, and E5 are residual pathways (shown in blue in Fig. 1), which represent the genetic and environmental influences on psychotic experiences that are independent of autistic traits
  2. Saturated saturated model of means and covariance, ACE sex diff. full ACE Cholesky decomposition, which included quantitative sex differences for all parameters, ACE const. constrained ACE Cholesky decomposition, with parameters fixed to be equal across sexes, −2LL fit statistic, df degrees of freedom, Par. parameters, AIC Akaike’s Information Criteria, BIC Bayesian Information Criteria, A additive genetic influences, C shared environmental influences, E nonshared environmental influences
  3. aIndicates best-fitting model