Measures and composite concepts useful in clinical practice and diagnosis may not translate into research and clinical trial endpoints. We will discuss endpoint introspection when using, or choosing not to use, composite endpoints especially when comorbidities are common. Patient or person reported outcomes often focus on broad domains that measure several subdomains, for example a physical health domain may measure physical function, symptoms such as pain and fatigue, sleep/wake disturbance and other subdomains. We will discuss the development and clinical research use of the Patient Reported Outcomes Measurement Information System (PROMIS), an NIH Roadmap initiative designed to improve assessment of self reported symptoms and other health related quality of life domains of physical, mental, and social health across many chronic diseases and the general population.