Discriminant validity is the degree to which a measure is not associated with measures of theoretically unrelated constructs. It supports construct validity by showing that a measure remains distinct from concepts it should not represent. section 6.3.2
Assess discriminant validity by comparing relationships among measures:
- Use correlations between the target measure and theoretically unrelated measures; a weak relationship supports discriminant validity. section 6.3.2
- Compare these relationships with convergent measures, which should generally show stronger associations because they assess related constructs. section 6.3.2
- Treat the result as one part of construct validity, alongside convergent validity, rather than as evidence that the measure predicts an external criterion. section 6.3.2
Net Promoter Score
When evaluating an NPS question as a measure of likelihood to refer, examine whether it correlates with referral behaviors while remaining distinct from theoretically unrelated measures. section 6.3.2
