| MEASUREMENT PROPERTIES | |
| Limitations | |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Internal consistency for the JAFAS varies from moderate to good, with a Cronbach's α ranging from 0.81 to 0.92 |
| 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 | Tested |
| Standard error of measurement (SEM), smallest detectable change (SDC) or Limits of agreement (LoA) (Describe) |
Lovell et al found that the mean interitem correlation of the JAFAS in the population with JIA was 0.36, indicating that the items capture different aspects of function |
| 2. VALIDITY | |
| A. Content validity: face validity | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
With regards to content validity, the JAFAS was developed from a range of tasks derived from the McMaster Health Index Questionnaire, the Arthritis Impact Measurement Scale, and the Health Assessment Questionnaire. An expert panel of pediatric physical and occupational therapists experienced in working with children with JIA reviewed items to ensure that the activities involved all aspects of the body during daily activities and were easy to measure objectively. |
| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description | |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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