[Quality of life in children: what is a good evaluation tool?]

The tools most often used to measure subjective data in health, especially quality of life, are based on psychometry. The object of this article is to provide as simply as possible an explanation to the specific methodological aspects of this field. As an example, the child version of the Children Health Questionnaire (CHQ-CF87) is used to study how to demonstrate the qualities required for a good assessment tool: acceptability in practice, responsiveness, reliability and validity. These qualities must be reassessed when a given tool is translated into another language.