The basic principles of the rating scale procedure have been outlined, including the Likert scale, the Guilford criteria for item definitions, and the Guttman and Rasch criteria for item combinations. With these criteria, headache rates among the core symptoms of anxiety and depression. Next, we have discussed one of the prevailing scales for headache, the Waters Headache Questionnaire (WHQ), with a multiaxial approach. The WHQ thus contains a severity axis, a diagnostic axis, and a personality axis. Previous studies on the validity of the WHQ, including factor analysis, have shown that migraine and muscular headaches are not mutually exclusive categories. Studies to validate a two-dimensional diagnostic system of migraine and non-migraine headache by Rasch models are discussed. In the field of personality it was suggested, when using questionnaires like the WHQ, to focus on the concepts of acquiescence and dissimulation. Supplemental axes such as "severity of psychosocial stressors" and "social functioning" or "quality of life" should be considered in future research.