What is validity and what different forms of it exist?
Validity – refers to the truth-value of a research project. How can we say whether
the reported results are true?
Measurement validity: measuring what you say you are measuring
Face validity: the degree to which measures (ex. Questions on a questionnaire)
successfully indicate concepts.
Criterion validity: comparing the results of questions with established indicators of
the same concept. Ex. Comparing the results of an interview survey of people’s
health status with the results of a doctor’s examination
- If the results differ from the doctor’s assessment the interview would be
judged to have poor validity
Construct validity: evaluates a measure according to how well it conforms to
expectations derived from theory
Ex. If health status is related to social class we would expect our measure of health
status to give different results for people from different social classes.
Internal Validity: the extent to which causal statements are supported by the
External Validity: the extent to which findings can be generalized to populations or
How does validity differ fr