1993; Young et al., 2008). However, this strategy is not applicable to the ALSPAC data because the measures of alcohol use and antisocial behavior varied over time. Accordingly, we used the item response theory approach to calibrate alcohol use and antisocial behavior factors to the equivalent scales across measurement occasions (McArdle et al., 2009). Setting measurement parameters of common items equal across time calibrates the measures of latent variables by different sets of indicators across time to a commensurate scale.
