How to Develop and Validate a GI Questionnaire

Advances in medicine rely on scientific methods, and objective measurements are critical for applying these. However, medicine is essentially subjective in many senses, especially in information recalled by patients, and other such outcomes. Questionnaires are intended to measure, as objectively as possible, these subjective elements. As measurement instruments, they should be developed and the quality of the measurement tested. The process of developing a questionnaire is more than just writing questions; the objective of the questionnaire should direct the process and issues such as how it will be used should be considered. Just developing the questionnaire is not enough; it must be validated to become an instrument that can be trusted. Validation is a systematic process for testing the feasibility, reliability, and validity of a questionnaire. Reliability is like precision (the answers remain the same when the process is repeated) and validity is like accuracy (the answers represent the truth).