The Marijuana Screening Inventory (MSI-X): concurrent, convergent and discriminant validity with multiple measures.

This study evaluates the concurrent, convergent and discriminant validity between the MSI-X and five other instruments completed by 107 adults. Pearson correlation analysis with follow-up t-tests found concurrent validity between the MSI-X, Drug Abuse Screening Test (DAST-20), five Substance Abuse Subtle Screening Inventory (SASSI-3) subscales, a Diagnostic Statistical Manual (DSM) IV-TR Guided Marijuana Inventory, and two Addiction Severity Index variables. As evidence of MSI-X discriminant validity, no correlations were found with three alcohol measures. Convergent validity, determined by t-test associations between MSI-X total problems with SASSI-3 substance dependence scores, supported the MSI-X > or =6 scoring cutoff. Overall, the findings support MSI-X concurrent, convergent and discriminant validity.