Development and Validation of the Marijuana Motives Measure Short Form.

Marijuana motives are a proximal variable to marijuana use. This research aimed to adapt and validate the short form of the Marijuana Motives Measure (MMM; Simons, Correia, Carey, y Borsari, 1998), the MMM SF, in Spanish.  The sample comprised 232 participants (mean age = 25.11 (7.58), 50.43% males) who had tried marijuana at least once in their lifetime. Item and Rasch analyses were performed to choose the final pool of 15 items. Confirmatory Factor Analysis (CFA) showed an adequate 5-factor structure (S-BX2(80) = 121.30, p = .002; NNFI = .944; CFI = .958; IFI = .959; MFI = .915; RMSEA = .047(0.029, 0.063); AIC = -38.70), and the multi-group CFA between males and females showed acceptable fit indices (S-BX2(160) = 230.01, p = .000; NNFI = .900; CFI = .924; IFI = .927; MFI = .860; RMSEA = .062(.043, .078); AIC = -89.99). The questionnaire indicated metric (S-BX2diff (15) = 13.61, p = .556)), scalar (S-BX2diff (15) = 23.15, p = .081)) and error measurement invariance (S-BX2diff (15) = 8.65, p = .895)) between gender groups. The internal consistencies and ordinal omega of the scales were between .79 and .90. In the regression analysis, enhancement, coping and low conformity motives predicted frequency and quantity of marijuana smoked. The best predictor of frequency and quantity consumed during the heaviest smoking period was enhancement, while coping and, to a lesser extent, low conformity, were the only predictors of cannabis-related problems when marijuana frequency and quantity were controlled for.  The MMM SF shows adequate psychometric properties and is a suitable instrument to assess marijuana motives, especially during time-limited sessions.