Dealing with Zeros: Adolescent Drug Use, Perceived Disapproval, and Perceived Harm.

Because studies examining youth drug use often have data with a high proportion of zeros, they often do not meet the assumptions for univariate or linear regression analyses that are typically used. We demonstrate the use of zero-inflated negative binomial regression models to address excessive zeros in drug use frequency on perceptions of disapproval and perceived harm among middle and high school students ( N  = 522). We found that perceptions of parent disapproval were a better predictor of marijuana use ( p  = .01) than peer disapproval. Perceived harm was related to marijuana use ( p  = .04). Researchers should consider using zero-inflated negative binomial regression models when examining youth drug use.