Table 3 gives the descriptives of the marginal posterior distribution of the parameter values. The estimate for heritability based on the mean of the posterior distribution is 73%. The main effect of sex on the latent trait, with females scoring higher than males, is just significant, as zero is not included in the central 95% credibility region. Values of the β-parameters are all around zero or positive, indicating that the AP scale is most sensitive for individuals with considerable attention problems but has a hard time discriminating individuals with relatively few problems with attention. This results in the severely skewed distributions of sum scores. Table 3Descriptives of marginal posterior distributions for the AE variance decomposition model using the 1PL IRT model for polytomous items with a main effect for sexParameterMeanSD2½th percentileMedian97½th percentileσ2a0.840.070.710.840.99σ2e0.320.060.200.320.44δ−0.130.05−0.24−0.13−0.02β110.250.050.150.250.34β122.760.102.562.762.96β21−0.760.05−0.86−0.76−0.66β222.440.082.302.452.60β31−0.430.05−0.53−0.43−0.33β321.840.081.711.841.98β411.900.061.781.902.02β423.960.203.583.964.36β510.220.050.130.220.32β523.030.102.833.023.23β610.620.050.530.620.73β623.900.153.633.904.19β712.570.072.442.572.71β724.610.314.054.605.27h20.730.050.630.720.82Note: First index of the betas refers to the item (see Table 1) and the second to the threshold
