| MEASUREMENT PROPERTIES | |
| Limitations | |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Cronbach’s α for the baseline Impact Index scores was 0.85 (95% CI 0.83, 0.85) and for the follow-up scores was 0.91 (95% CI 0.89, 0.93). All four items in the Impact Index were highly correlated with one another. |
| B. Reliability intraobserver or test-retest | Not Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
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| C. Reliability interobserver or Measurement error | Not Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
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| 2. VALIDITY | |
| A. Content validity: face validity | Not Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
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| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description | |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
Assessment of predictive validity showed that in the frst model Impact Index was predictive of surgical choice (b=0.37, p<0.001, OR=1.45) indicating that those with greater Impact Index scores were more likely to choose to undergo surgery.When overall health was added into the model, the model is not improved (p=0.93); thus overall health is not a signifcant predictor of choice, but Impact Index is still a signifcant predictor of choice. Finally, in the third step the model is still not improved (p=0.23); thus, CCI and overall health are not signifcant predictors of choice, while Impact Index is still a signifcant predictor of choice. |