The analyses were based on a set of national representative data, called The National Survey on Drug Use and Health (NSDUH). The overall sample exceeds half a million records in order to conduct this 10 years trend analysis . In addition, the prevalence calculation was based on each survey year and adjusted for the multilevel sampling design of this national study.

The significant differences in prevalences of ecstasy and marijuana use between genders were examined by a meta-analysis, adjusting for other covariates, such as age, ethnicity, household income and population density. The analysis used hierarchical Bayesian linear models, which allow to combine and summarize the results obtained from multiple datasets collected in different survey years.