for the first stage of analyses we allowed the PID-5 facets of depressivity, restricted affectivity, and suspiciousness to organize on negative affectivity and detachment. Similarly, the PID-5 facet of hostility was included in both negative affectivity and antagonism. The set of indicators for each domain were subjected to confirmatory factor analysis in an exploratory structural equation modeling framework. All analyses were conducted in Mplus version 7.20 () and default settings were used (e.g., WLS estimator), unless otherwise specified. All facet scores were treated as ordinal indicators and the twins within each pair were treated as clustered observations. This software outputs three fit indices that we utilized for determining unidimensionality. The Comparative Fit Index (CFI) and Tucker-Lewis Index (TLI) both range from 0 to 1 with values above .95 and .90 indicating close and acceptable fits, respectively (). Root Mean Squared Error of Approximation (RMSEA) is a chi-squared based index of model fit. There is no hard and fast interpretation guideline for RMSEA, but generally values < .08 are considered of indicative of reasonable fit and those < .10 are often considered adequate (). Guided by these thresholds, we iteratively purified the initial facets within each domain in a way that balanced fidelity of construct with the requirement of essential unidimensionality. As our empirical focus was a comparison of the broad domains, we sought to retain as much variance within each instrument so that the construct we analyzed had high fidelity with the typical use of these measures. In this vein, putatively interstitial facets that loaded poorly on their primary domain were removed and tried in a second domain. For example, PID-5 rigid perfectionism obtained a superior fit on negative affectivity even though it sometimes loads on disinhibition in joint analyses (). Similarly, the facet of immoderation (alternatively titled impulsivity) from the IPIP-NEO is assigned to neuroticism, but obtained a better fit within the disinhibition domain. Ultimately, though, there were scales from each measure that did not load
for the first stage of analyses we allowed the PID-5 facets of depressivity, restricted affectivity, and suspiciousness to organize on negative affectivity and detachment. Similarly, the PID-5 facet of hostility was included in both negative affectivity and antagonism. The set of indicators for each domain were subjected to confirmatory factor analysis in an exploratory structural equation modeling framework. All analyses were conducted in Mplus version 7.20 () and default settings were used (e.g., WLS estimator), unless otherwise specified. All facet scores were treated as ordinal indicators and the twins within each pair were treated as clustered observations. This software outputs three fit indices that we utilized for determining unidimensionality. The Comparative Fit Index (CFI) and Tucker-Lewis Index (TLI) both range from 0 to 1 with values above .95 and .90 indicating close and acceptable fits, respectively (). Root Mean Squared Error of Approximation (RMSEA) is a chi-squared based index of model fit. There is no hard and fast interpretation guideline for RMSEA, but generally values < .08 are considered of indicative of reasonable fit and those < .10 are often considered adequate (). Guided by these thresholds, we iteratively purified the initial facets within each domain in a way that balanced fidelity of construct with the requirement of essential unidimensionality. As our empirical focus was a comparison of the broad domains, we sought to retain as much variance within each instrument so that the construct we analyzed had high fidelity with the typical use of these measures. In this vein, putatively interstitial facets that loaded poorly on their primary domain were removed and tried in a second domain. For example, PID-5 rigid perfectionism obtained a superior fit on negative affectivity even though it sometimes loads on disinhibition in joint analyses (). Similarly, the facet of immoderation (alternatively titled impulsivity) from the IPIP-NEO is assigned to neuroticism, but obtained a better fit within the disinhibition domain. Ultimately, though, there were scales from each measure that did not load
PID5%20IPIP%20IRT_accepted.docx