Descriptive statistics were computed in SASv9 (SAS Institute, 1999). As the items assessing craving in COGA/COGEND and FSCD were slightly different, a multi-group confirmatory factor model was used to determine (a) the factor loading (discrimination) and threshold (difficulty) for craving in the full SAGE sample and (b) to examine whether these parameters varied across the 3 contributing parent studies. Item response modeling was conducted in MPlus v5 (Muthen & Muthen, 2007).
