To bin or not to bin? A comparison of symptom frequency response formats in the assessment of health-related quality of life

The goal of this study is to compare three different types of retrospective frequency response formats on the Healthy Days Symptoms Module (HDSM). Responses are compared in terms of intra-individual consistency, psychometric value, and participant feedback about each type of response format.Respondents each completed three versions of the HDSM, where items were framed to elicit an open-ended frequency, a fixed choice frequency, or a vague...