Respondent selection by mail - Obtaining probability samples of health plan enrollees

OBJECTIVES. This study was done to assess the feasibility of respondent sel ection by mail to obtain random samples of both child and adult enrollees o f health plans when only subscriber contact information is available. METHODS. The subjects were enrollees of health plans covered under the poli cies of employees of the State of Washington. Subscribers were eligible for inclusion in the study samples if they had been enrolled for at least 6 mo nths and, depending on the test, had at least one child and/or a spouse enr olled under their policy. Subjects were randomly assigned to six groups: th ree approaches for sampling children, two approaches for sampling adults, a nd one test of parents' willingness to return a questionnaire about themsel ves. Child selection protocols involved asking respondents to complete eith er a child-only or a dual questionnaire, asking them to follow a decision r ule to choose a sample person, and collecting data in two phases, asking re spondents to return material twice. RESULTS. Results indicated that asking subscribers to select an adult respo ndent by mail was not a success. At least given the procedures we used, adu lts did not demonstrate good compliance with the respondent selection proce ss offered them. In contrast, parents proved willing to follow a more compl icated child selection rule and to do it nearly perfectly. CONCLUSIONS. parents will follow a decision rule to select an eligible chil d, but requiring this additional respondent selection step may be associate d with a slightly decreased response rate. Asking parents to return materia ls twice is feasible, but it is too cumbersome a procedure to be practical. It is possible to collect data about both an adult and a child using a dua l instrument; however, the increase in information is tempered by a decreas e in response rates.