Last Updated 03/23/2024

In a research study, refers to the extent to which the study accurately measures what it claims to measure. Validity refers to both the accuracy of the entire study as well as each step of the study. There are four types of validity:

  • Statistical conclusion validity asks if a finding is accurate. Is there adequate power, sample size? Are assumptions of statistical tests violated? Are measures reliable?
  • Construct validity asks how well the inferences made about higher level constructs represented in the study match (1) what was implemented and (2) what was measured as an outcome.
  • External validity asks whether a cause-effect relationship holds under variations in people, settings, treatment variables, and measurement variables.
  • Internal validity asks whether changes in the treatment condition impact changes in the outcome. Did something other than the treatment explain variation(s) in the measured outcome?

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