Validation of a questionnaire to measure people’s ability to assess claims about treatment effects

Abstract

Introduction: Every day, people are faced with claims about treatment effects through mass media, social media, or by word of mouth. Objective: To validate a Spanish-language questionnaire to measure the ability of an individual to assess claims about treatments effects. Method: A set of 22 multiple choice questions taken from the claim evaluation tools database were translated and applied to 172 children and 268 adults. Using a Rasch model, overall and individual item-person fit was explored, as well as the potential item differential functioning (based on gender, age and mode of administration), multidimensionality and local independence. Results: Overall item-person fit was appropriate. Four multiple-choice questions showed a poor fit. Reliability of the questionnaire was satisfactory with a person separation index of 0.7. Multiple-choice questions were unidimensional, and there was no specific dependency. Conclusion: A set of 18 multiple-choice questions with satisfactory fit was obtained. This is the first available questionnaire validated in Spanish to measure individuals’ ability to assess claims about treatment effects.