| MEASUREMENT PROPERTIES | |
| Limitations | <5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Not Tested |
| Cronbach's (Describe) |
Internal consistency reliability was excellent, with a Cronbach's α of 0.99. |
| B. Reliability intraobserver or test-retest | Not Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
In a study of 74 children with JIA of mixed subtypes, the test-retest reliability of the revised ASK demonstrated excellent reliability (ICC = 0.91). In a study in which the ASK was mailed to 40 parents and children twice, the test-retest reliability was also good (ICC = 0.97 for ASKp and ICC = 0.98 for ASKc.) |
| 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 |
Tested |
| Hypotheses-testing | Not Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
Young et al also demonstrated construct validity with Rasch analyses, which confirmed that all items measure the same construct. |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
With regard to criterion validity, Young et al found that when tested with a group of 200 children, the ASK was strongly correlated with parent-reported C-HAQ scores (r = 0.81) and clinician observation (r = 0.92). A significant difference in ASK scores according to the clinician's global ratings of disability (P < 0.001) was found. |