Three Ways of Looking at Marijuana Consumption Data

Here’s a nice chart from Andrew Sullivan on marijuana consumption in Colorado. It illustrates a point that has been made many times by drug policy analysts such as Mark Kleiman and Beau Kilmer: The total volume of pot consumption is accounted for almost entirely by users who smoke every day or nearly every day. Envisioning how different stakeholders would respond to this evidence can be helpful both for appreciating the impossibility of value-free evidence-based policy and for understanding one of the basic dilemmas of legal marijuana regulation.

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AT THE PUBLIC HEALTH CONFERENCE: “Colleagues, you can see from this chart that not all marijuana users are of equal concern to us. Some people use the drug rarely, and we know that such users tend to be high social capital individuals who could set their lives right in the unlikely event that they did develop a drug problem. So we should focus instead on these heavy users in the bottom two bars of the chart, who tend not incidentally to be people with less education, less income and poorer access to health care. The evidence we have shows that the primary risks of this drug, for example marijuana dependence, mental health problems and poor school and work performance, are concentrated in the subset of people who use every day or almost every day. Let us therefore resolve to keep the size of this group as small as possible through high taxes that discourage heavy consumption, caps on THC content that reduce the ability of the drug to promote dependence and limits on advertising and points of sale in vulnerable communities.”

AT THE CORPORATE BOARD MEETING: “Well friends, you can see from this chart that not all of our customers are of equal concern to us. We can’t make much money from the people in the top few bars of the chart, so we should focus mainly on the heavy users who provide us the bulk of our revenue. We need to move as much of the population as possible into this high-revenue bracket. So let’s all agree to press for lower taxes, higher THC content and as much advertising and as many retail locations as possible in the communities where our best customers tend to live.”

AT THE STATE LEGISLATURE: “Fellow committee members, as you know we have seen this chart twice today, once when the public health advocates visited and again when the marijuana industry lobbyists visited. Both groups agreed on the evidence but they wanted us to respond to it in opposite ways. And that’s not the end of what we have to consider. The state budget analyst’s office has calculated that almost 90% of the marijuana tax revenue we wanted from legalization comes from the people in the bottom bars of this chart. We care about public health but if we implement policies that make too many of those heavy marijuana users quit, the tax revenue hit we will take might force us to sacrifice other important priorities.”

Author: Keith Humphreys

Keith Humphreys is a Professor of Psychiatry at Stanford University. His research, teaching and writing have focused on addictive disorders, self-help organizations (e.g., breast cancer support groups, Alcoholics Anonymous), evaluation research methods, and public policy related to health care, mental illness, veterans and drugs. He is the author or co-author of numerous books and scholarly articles, and has written for the New York Times, Wall Street Journal, Washington Post, The Guardian (UK), the San Francisco Chronicle and other media outlets. When he is not in the San Francisco Bay Area, he is usually in London, where he is an ad hoc policy adviser to the national and city government, an honorary professor of psychiatry at Kings College, a senior editorial adviser to the journal Addiction, and a member of The Athenaeum. When he is not in the San Francisco Bay Area or London, he is usually in Washington D.C., where he serves as a frequent science and policy advisor to federal agencies, and where he has served previously as an appointee to a White House commission and several Secretarial task forces. From July 2009-2010, he served as Senior Policy Advisor at the White House Office of National Drug Control Policy. When he is not in the San Francisco Bay Area or London or Washington D.C., he is usually in the Middle East, where since 2004 he has volunteered in the international humanitarian effort to rebuild Iraq’s mental health care system. This work has taken him to Turkey, Egypt, Iraq, Jordan and Lebanon to teach and consult with Iraqi health professionals and policy makers.