Translation, development and psychometric properties of health related measures-Part 2: construct validity, reliability and responsiveness

Objective (s): Data collection is one of the important stages of research process and requires valid and reliable instruments. The aim of this article was to introduce important steps of translation and construction process of a questionnaire. Adopting an appropriate instrument for research and developing an optimal instrument needs knowledge on psychometric criteria. The present paper explains the construct validity reliability and responsiveness as the important components of psychometric properties of health related instruments. Methods: The present paper was written based on exisiting documentaries. Results: There are different methods for evaluating construct validity, which include structural validity (factor analysis), hypothesis testing, convergent and discriminant validity, and cross-cultural validity. Criterion validity is also a type of validity, which can improve the quality of an instrument if being applicable. Reliability is an essential part of psychometric evaluation, which includes internal consistency, stability, equivalency and standard error of measurement. Instrument developers have often been concerned with internal consistency and stability. Examining standard error of measurement as an important component of reliability has been ignored in the development of most instruments. Responsiveness is approved if the smallest detectable change is less than the clinical minimal important change. Furthermore, the area under the ROC curve can also be used for examining responsiveness. Floor and ceiling effects exist if more than 15% of respondents get the highest or lowest possible scores. Conclusion: Psychometric knowledge should be considered as basic requirement of translation and development of health-relate measures. This could help investigators to collect valid and reliable information when collecting the data.