Construct validity can also be assessed by measuring the extent to which a scale correlates positively with other measures that address the same construct (convergent validity). Thus, moderate to high positive correlations (r = .32 to .76) were found between the SDS total score and frequency of cannabis use [23,24], amount of cannabis use [24] and the number of DSM-IV dependence criteria [23,24]. In addition, Legleye et al. [15] reported several correlations of the CAST score with psycho-pathological dimensions of the Problem Oriented Screening Instrument for Teenagers (POSIT) [28] that measures psychological, physical and social health impairments. Students with higher CAST scores reported worse physical and mental health and more school problems.
