An enumeration method of determining the prevalence of users and operatives of cocaine and heroin in Central Harlem

Abstract

Introduction: The investigators estimated the number and characteristics of crack, powder cocaine and heroin users and distributors (“operatives”) in Central Harlem. Methods: Central Harlem was divided into 45 primary sampling units (PSUs) with 2 years of drug allegation data from the New York Police Department (NYPD) organized in three strata, those having high, middle or low levels of allegations. In nine randomly selected PSUs, interviewers employed chain referral sampling procedures that were steered by using a nomination technique. Results: Within sampled PSUs, 657 respondents nominated 5756 others for a total of 6413. Seven indicators identified 1007 unique individuals among 2835 nominated by two or more respondents, totaling to 4585 unique persons. These drug users and operatives were divided by the total number of persons in these PSUs according to the 1990 census to estimate the number of drug users and distributors in the 36 PSUs not sampled and for all 98 725 residents of Central Harlem. Approximately 13.4% of Central Harlem residents were estimated to be users of crack, powder cocaine and/or heroin with no roles in drug distribution. Approximately 6.7% of Central Harlem residents were estimated to be operatives of these drugs, some of whom may also have been users. Conclusions: Enumeration techniques can be a basis for projecting prevalence estimates for crack, powder cocaine and heroin users and operatives in a large urban geographic area.