Enhancing validity through cognitive interviewing. A methodological example using the Epilepsy Monitoring Unit Comfort Questionnaire

Abstract

Aims: To identify problematic items, assess completeness and user-friendliness, and undertake modifications to enhance face validity of the newly developed Epilepsy Monitoring Unit Comfort Questionnaire. Design: Qualitative-descriptive cross-sectional study. Methods: Five iterative rounds of cognitive interviewing were conducted with members of the target population between July - November 2017. Think-aloud technique, verbal probing, and observation were used, to assess how respondents understood and answered questions. Data analysis was based on the framework method; an eight-column framework matrix was created for this purpose. Results: In 25 interviews, problems regarding completeness of the item pool, comprehension of items, retrieval of information, judgment while finding answers and reporting the appropriate responses could be detected. According to the results, 27 items remained unchanged, 11 items were reworded, and six items were added. Instructions section of the questionnaire was reworked, too. Conclusion: Although time-consuming, cognitive interviewing turned out to be a valuable approach for revealing problems in an instrument, which would, otherwise, remain undetected and threaten validity.