THE FEASIBILITY AND ACCURACY OF ANONYMIZED RECORD LINKAGE TO ESTIMATESHARED CLIENTELE AMONG 3 HEALTH AND SOCIAL-SERVICE AGENCIES

This study was designed to test the effectiveness of three computerize d methods of record linkage, using minimal identifiers. The goal of th e linkage was to determine the proportion of persons receiving Public Health Nursing Services (n = 5,749) who also receive income assistance from the region (n = 38,800) or the province (n = 16,741). The first linkage method was based on full agreement of a number of variables (d eterministic matching) and the second was based on the likelihood of t he match (probabilistic matching). The third method combined informati on from methods 1 and 2. Method 3 proved to be the most effective link age technique, with a specificity of 0.98 and sensitivity of 0.94. The linkage showed that only 17% of the Public Health clientele received income assistance from the region or province, much lower than expecte d. Factors which have probably led to an underestimate are discussed.