Estimating the point accuracy of population registers using capture-recapture methods in Scotland.

STUDY OBJECTIVE

To estimate the point accuracy of adult registration on the community health index (CHI) by comparing it with the electoral register (ER) and the community charge register (CCR).

DESIGN

Survey of overlapping samples from three registers to ascertain whether respondents were living at the addresses given on the registers, analysed by capture-recapture methods.

SETTING

Aberdeen North and South parliamentary constituencies.

PARTICIPANTS

Random samples of adult registrants aged at least 18 years from the CHI (n = 1000), ER (n = 998), and CCR (n = 956).

MAIN RESULTS

Estimated sensitivities (the proportions of the target population registered at the address where they live) were: CHI--84.6% (95% confidence limits 82.4%, 86.7%); ER--90.0% (87.5%, 92.5%), and CCR--87.7% (85.3%, 90.3%). Positive predictive values (the proportions of registrants who were living at their stated addresses) were: CHI--84.6% (82.2%, 87.0%); ER--94.0% (90.9%, 97.1%), and CCR--93.7% (91.7%, 95.7%).

CONCLUSIONS

The CHI assessed in this study was significantly less sensitive and predictive than the corresponding ER and CCR. Capture-recapture methods are effective in assessing the accuracy of population registers.