Validated scales, also known as instruments or inventories, are a collection of questions intended to identify and quantify constructs based on educational theory such as motivational variables (e.g., self-efficacy), emotional states (e.g., anxiety), cognitive aspects (e.g., self-esteem), personality characteristics (e.g., introversion) and other unobservable constructs. Two very important aspects or psychometric properties of a validated scale are its reliability and validity. [more] Explore prior research for previously constructed scales that have adequate reliability and validity. If you cannot find a scale that measures your construct of interest or with sound psychometric properties, you may need to develop your own instrument. However, developing a validated scale is difficult, time consuming, and requires skills beyond what can be taught here. For a complete discussion of creating and using validated scales, see DeVellis (2003) or Worthington and Whittaker (2006).
DeVellis, R. F. (2003). Scale development: Theory and applications (2nd ed.). Newbury Park, CA: Sage Publications.
Worthington, R. L., & Whittaker, T. A. (2006). Scale development research: A content analysis and recommendations for best practices. The Counseling Psychologist, 34, 806-838