Table 3 The process of item reduction following initial reviews by the research team and psychometric assessment
Stage | Items (n) | Items reviewed/merged/removed (n) | Items kept (n) |
|---|---|---|---|
Initial pool of items, review by the research team: First stage | 154 | 48 | 106 |
Review by the research team: Second stage | 106 | 15 | 91 |
Review by the research team: Third stage | 91 | 18 | 73 |
Qualitative face validity | 73 | Face-to-face interview with 15 older patients. 3 items merged and 10 items reviewed and edited. | 70 |
Quantitative face validity (impact score) | 70 | 3 items with impact score < 1.5 removed | 67 |
Qualitative content validity | 67 | 3 items merged and 44 items reviewed and edited. | 64 |
Quantitative content validity, content validity ratio (CVR) | 64 | 19 items with CVR < 0.49 removed | 45 |
Quantitative content validity, content validity index (CVI) | 45 | No items removed: CVI > 0.79, kappa coefficient > 0.74 | 45 |
Item analysis | 45 | 8 items with item-total correlation coefficient < 0.3 removed | 37 |
Construct validity (principal component analysis) | 37 | 10 items removed due to factor loading < 0.3 | 27 |
Final questionnaire | 27 |