Wednesday, February 23, 2005
Yesterday Vice Squad mentioned (twice) substitutability (or complementarity) between alcohol and tobacco. Today we look at some new evidence concerning the demand relationships among cannabis, alcohol and cigarettes. The evidence comes from a recent working paper by Jan C. van Ours, "Cannabis Use When It's Legal." As the title suggests, the paper is based on data from Amsterdam, although even there, cannabis remains officially illegal, though sales in offically recognized coffee houses are regulated and tolerated. The main issues that van Ours examines are versions of the gateway theory: does initiation of alcohol or cigarette use lead to more cannabis use, and vice versa? The result, using survey data from 1994, 1997, and 2001, is that cannabis use reduces the initiation of alcohol use -- that is, alcohol and cannabis are intertemporal substitutes -- while tobacco use increases the initiation of cannabis consumption. In this sense, tobacco consumption is a gateway to marijuana use, but marijuana use dissuades drinking. Approximately 5% of the female respondents and 10% of the male respondents are current users of the entire drug trio -- alcohol, tobacco and cannabis -- while fewer than 2% of the respondents have consistently abstained.