Consequences of measures to optimize response rate for research in medicalsociology: The example of a telephone survey of elderly people

Based on a telephone survey of elderly people (greater than or equal to 60 years) the impact of measures to optimize response rate (repeated telephone calls and converting temporary refusals) on the sample structure is analyz ed. Results show slight differences between persons who can be reached easi ly and those who are difficult to contact as far as their sociodemographic, socioeconomic and health related characteristics are concerned. Moreover t here are no significant differences between temporary refusals and cooperat ive respondents on these characteristics. Differences are considerable howe ver on multivariate relationships between sociodemographic, socioeconomic a nd psychosocial variables on the one hand and subjective health on the othe r. Results indicate that nonresponse has an effect on relationships between variables which are essential for research in medical sociology. This effe ct clearly shows the necessity of measures to increase response rate for re ducing nonresponse bias especially in surveys of elderly people.