Psychometric evaluation of the marijuana and stimulant effect expectancy questionnaires for adolescents.

Alcohol expectancies are important in the mediation and prediction of alcohol use. Expectancies for the effects of other drugs, although less well delineated, appear equally important. Therefore, development and validation of expectancy measures for drugs other than alcohol is necessary for evaluating the importance of these constructs. We examined the factor structure, reliability, and validity of the Marijuana Effect Expectancy Questionnaire (MEEQ) and the Stimulant Effect Expectancy Questionnaire (SEEQ) in clinical and community samples of adolescents as they moved into young adulthood (N=279). Confirmatory factor analyses (CFAs) supported the a priori factors, and we found good reliability for most individual scales. Temporal stability and convergent and discriminant validity of drug effect expectancies were supported in this sample of adolescents and young adults. Drug effect expectancies were associated with drug preference and drug use patterns over 2 years. Use of these measures may aid our understanding of the etiology and course of marijuana and stimulant involvement during adolescence and young adulthood.