Strategies for estimating behavioural frequency in survey interviews

When people answer survey questions of the form "During the past month, how many times did you... ?" their responses provide valuable data for researchers and policy makers. Yet the way respondents produce their answers to these "behavioural frequency questions" is not well understood. This article demonstrates that survey respondents can use an array of distinct estimation strategies, depending on what information is available in their memories. The kind of event information that people use is related to factors such as the regularity of occurrence, similarity of one episode to the next, and frequency. In a study conducted as a telephone survey, respondents' verbal reports and response-time patterns indicate that they usually answer behavioural frequency questions by either retrieving and counting episodes, retrieving or estimating rates of occurrence, or converting a general impression of frequency into a numerical quantity. The third strategy should be of particular concern to survey researchers because respondents provide a quantitative estimate without any relevant numerical knowledge. The set of strategies and the factors that influence their use are integrated into a statistical model that could help survey practitioners to improve data quality and memory researchers to broaden their perspective.