Table 2.
Measure | Definition | Common methods of assessment |
Interpretationa |
---|---|---|---|
Validity (degree to which an instrument measures the concept it is intended to measure)28,30,31,59 | |||
Content validity | Extent to which the instrument includes the most relevant and important aspects of a concept54 |
Stakeholder focus groups, interviews, surveys |
Qualitative evidence from development and pre-testing60 |
Construct validityb | Evidence that relationships among items, domains, and concepts conform to a priori hypotheses28 |
Correlation statistics |
≥0.70 supports strong correlation |
Congruent | Extent to which measure correlates with measure assessing the same construct |
||
Known group | Extent to which measure is sensitive to differences and similarities in groups with known attributes |
||
Responsiveness | Extent to which instrument can detect changes in the construct being measured over time30 |
Score change statistics |
Statistically significant difference in scores pre- and post-clinically relevant events29 |
Reliability (degree to which an instrument is free from measurement error)30, 31,59 | |||
Internal consistency reliability |
Degree of the interrelatedness among the items in a multi-item measure30,31 |
Cronbach’s α | ≥0.70: adequate internal consistency60 |
Test-retest reliability |
Measure of the ability to provide consistent scores over time in a stable population30 |
Intraclass correlation coefficient; Kappa statistic |
≥0.70: supports test-retest reliability29 |
Interpretation score thresholds are not well established and may differ across populations and sources.
Construct validity was considered as congruent and known group validity as these were the construct validity sub-types most commonly assessed in identified instruments.