This is the second edition of the only practical guide for clinicians developing tools to measure subjective states, attitudes, and other 'non-tangible' outcomes in their patients. This new edition has been thoroughly revised to incorporate all the latest research published since the first edition. Additions to this edition include a chapter on ethics and a discussion of reliability and generalizability theory. Throughout, the authors provide a methodical, step-by-step approach, explaining both the theory and the practical applications of health measurement scales, to guide the reader through the development of their own scales. These features combine to provide the most up-to-date guide to measurement scale development available. Written in a concise and intelligible style, it enables both experienced researchers and novices to develop accurate, sensitive and easy-to-use measurement scales of their own. This is an essential book for anyone who uses or would like to use rating scales in their clinical practice.