U.S. flag

An official website of the United States government, Department of Justice.

How Much of the Cocaine Market Are We Missing? Insights From Respondent-Driven Sampling in a Mid-sized American City

NCJ Number
Drug and Alcohol Dependence Volume: 147 Dated: February 2015 Pages: 190-195
Date Published
February 2015
6 pages
This paper uses respondent-driven sampling (RDS) of drug users in a mid-sized American city to estimate the shares of cocaine (powder and crack) users and expenditures that are attributable to different combinations of these groups.
Studying markets for illegal drugs is important, but difficult. Data usually come from a selected subset of consumers, such as arrestees, treatment clients, or household survey respondents. There are rarely opportunities to study how such groups may differ from other market participants or how much of total consumption they represent. The current study found that those arrested in the last year accounted for 34 percent of past-month cocaine users and 40 percent of past-week cocaine spending in the RDS sample. Augmenting past-year arrestees with those who received treatment in the past year increases these values to 44 percent (users) and 55 percent (spending). These results suggest that estimates based only on people who were arrested and/or treated in the past year would have to be inflated by 100-200 percent to capture the market totals. Adding those who own or rent their place of residence increased coverage in this study to 76 percent (users) and 81 percent (spending), suggesting that in theory the inflation factor could be reduced to 23-32 percent by supplementing data on arrestees and treatment populations with household data, although in practice rates of under-reporting by survey respondents may make coverage (sampling frame) a secondary concern for household surveys. (Publisher abstract modified)

Date Published: February 1, 2015