Application of cognitive interviewing to improve self-administered questionnaires used in small scale social pharmacy research.

Validating questionnaires for social pharmacy research with smaller sample sizes can be unnecessarily time-consuming and costly, a solution to this is cognitive interviewing with 2 interviews per iteration. This paper shows how cognitive interviewing with pairs of interviews per iteration of the questionnaire can be used to identify overt and covert issues with comprehension, retrieval, judgment and response experienced by respondents when attempting to answer a question or navigate around the questionnaire. When used during questionnaire development in small scale social pharmacy research studies cognitive interviewing can reduce both respondent burden and response error and should result in more reliable survey results. The process of cognitive interviewing is illustrated by a case study from the development of the Perspectives on Progesterone questionnaire.