construct validity
the degree to which a test or instrument is capable of measuring a concept, trait, or other theoretical entity. For example, if a researcher develops a new questionnaire to evaluate respondents’ levels of aggression, the construct validity of the instrument would be the extent to which it actually assesses aggression as opposed to assertiveness, social dominance, and so forth. A variety of factors can threaten the basic construct validity of an experiment, including (a) mismatch between the construct and its operational definition, (b) various forms of bias, and (c) various experimenter effects and other participant reactions to aspects of the experimental situation. There are two main forms of construct validity in the social sciences: convergent validity and discriminant validity.