| MEASUREMENT PROPERTIES | |
| Limitations | English only |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
The person-separation index, used to measure internal consistency on the final 20-item instrument, was reported as 0.84. |
| B. Reliability intraobserver or test-retest | Not Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
The TIQ-20 test-retest intraclass correlation coefficient was 0.76 (95% CI 0.61-0.85). |
| C. Reliability interobserver or Measurement error | Not Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
|
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
Twenty-five people with tophaceous gout (22 men; median age, 66 years; median gout disease duration, 26 years) participated in semistructured interviews that explored their experiences and perceptions of tophi, as the first step to developing a patient-reported Tophus Impact Questionnaire. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
The TIQ-20 responses fit the Rasch model and demonstrated unidimensionality, adequate precision, absence of differential item functioning, and adequate person separation index. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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