Does legalization increase teen marijuana use? A case of dueling studies

A study published this week in JAMA Pediatrics contradicts one published last month in the American Journal of Public Health. Both studies used data from the Youth Risk Behavior Survey conducted every other year by the Centers for Disease Control and Prevention.

The newer study analyzed YRBS data from 1993 to 2017. It finds that the eleven states that have legalized marijuana for recreational use are associated with an 8 percent decreasein the odds of past-month adolescent marijuana use and a 9 percent decrease in the odds of frequent marijuana use (10 or more times in the past month).

These findings directly contradict last month’s study which finds a 10-fold increase in past-month adolescent marijuana use over roughly the same time. This researcher analyzed YRBS data from 1991 to 2017.

What are we to make of such a jarring contradiction?

Following the old adage “when in doubt, ask,” we’ve decided to write the authors of both studies and ask them to explain how their analyses of the same survey over nearly the same time could result in such different outcomes. We will publish their explanations in a future issue of The Marijuana Report as soon as we hear from them. Stay tuned.

Read JAMA Pediatrics article here. Read American Journal of Public Health abstract here.

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