I'm trying to get chi-square fit index of my univariate ACE model. I tried to use mxRefModels(ACEFit) and then use mxCompare between the mxRefModels output and my ACE model (ACEFit), but it returned NA for the p value
base comparison ep minus2LL df AIC diffLL diffdf p
Saturated twinACE 0 NA 0 NA NA NA NA
Saturated twinACE twinACE 6 879.7042 178 523.7042 NA 178 NA
Independence twinACE 0 NA 0 NA NA NA NA
Independence twinACE twinACE 6 879.7042 178 523.7042 NA 178 NA
-Can the mxRegModels funcion be used? Since in the help it states: "One potentially important limitation of the mxRefModels function is for behavioral genetics models."
-How should I modify previously posted (https://openmx.ssri.psu.edu/sites/default/files/UnivariateTwinAnalysis_MatrixRaw-3.R) ACE model definition to get the Saturated and Independence models if mxRefModels can not be used?
-How do I get df values that are similar to ones that I would get in other softwares (Mplus), because 178 seems a bit to much, does this alter the calculation of the chi-square fit index?
I would really appreciate anyone's help!!