Marijuana use and social contacts.

Results for logistic regression of ego drug use behavior at Wave II (1 =  used marijuana in past 30 days, 0 =  did not use) on Wave I covariates is shown in first three columns. Results for ordinary least squares regression of number of times ego uses marijuana at Wave II on Wave I covariates is shown in second three columns. The results suggest that both drug use and non-use may spread, but the spread of use is significantly stronger.