Does Response Format Matter? The Psychometric Effects of Filter Questions on Self-Reported Symptom Frequencies

The presence-severity response format uses a filter question to ask about the presence of a symptom, followed by a question about the severity of that symptom. Only an affirmative response to the filter question triggers the follow-up question. Despite its widespread use, little research has compared the psychometric properties of the presence-severity response format to those of the traditional single-item response format. The purpose of this research was to understand how filter questions influence item responses and characteristics on several short health-related questionnaires. Using two different experimental designs, we find that depending on the construct being measured, the inclusion of a filter question can have a substantial effect on people's responses, and in turn, the psychometric properties of the items. Overall, the presence-severity response format results in a reduction in symptom reporting and loss of information about individual differences, particularly for people experiencing mild symptoms. Measurement recommendations are provided.