Table 1 Criteria used to assess content validity strength and psychometric strength
Content validity strength | Psychometric strength | |
|---|---|---|
Measures | • Target patient indication • Development process – Literature reviews (concepts or instruments) – Expert input/interviews – Patient participation (concept elicitation and/or cognitive debriefing interviews) | • Internal consistency reliability [30] Cronbach’s alpha > 0.7 • Reproducibility/test–retest reliability [31, 32] ICC > 0.7 • Construct validity [33] Correlation coefficients range from ≥ 0.3 to ≥ 0.6 • Minimum clinically important difference [34] Value(s) reported for PRO instrument • Ability to detect change Demonstrated for PRO instrument |
Scoring | ||
Strong | • Developed for target indication • Development process with involvement of patients, literature reviews and clinician experts | • 4 or 5 psychometric properties meeting threshold values |
Medium | • Developed for target indication • Development process lacking patient input | • 2 or 3 psychometric properties meeting threshold values |
Weak | • Not developed for target indication OR • Just one type of input in the development process | • 0 or 1 psychometric properties meeting threshold values |