How valid are responses to questions about behaviour in hypothetical illness situations?

Questions concerning the respondents' actions in response to hypothetical illnesses have been used in a number of studies of illness behaviour and health service utilization, but the answers obtained have never been validated by direct comparison with the respondents' behaviour during episodes of real illness. Five hundred and fifty-four questionnaires were returned by parents giving details of how they would respond to hypothetical episodes of cough, fever and sore throat in their children. During a two-month period of recording, the children suffered 78 episodes of one or other of these symptoms which led to a consultation. The aim of this study was to compare the parents' responses to the hypothetical situations in the questionnaire with what they said they had done before each of these consultations for real illness. The comparison concentrated on the intervals that parents waited before requesting consultations, and on their medication of their children. The parents' responses to the questionnaire were poor predictors of their reported behaviour during actual illness episodes.