Refusal rates in a longitudinal study of older people: implications for field methods.

Use of a carefully designed refusal conversion protocol at first follow-up in a longitudinal study of a representative sample of over 4,000 older people was investigated. Respondents who refused initially did not differ from respondents by age or gender but were more functionally independent, citing disinterest most frequently as the reason for refusal. The protocol was successful in convincing 43 percent of these initial refusals to continue participation, but less successful with proxy respondents (27% converted). Most of the refusals that were converted were done by telephone at minimal cost. Results show that it is possible, given appropriate field methods, to retain the very old and disabled in longitudinal studies.