| MEASUREMENT PROPERTIES | |
| Limitations | <5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
α = 0.93 (whole questionnaire) Mobility: α = 0.83 Bending down: α = 0.88 Neck movements: α = 0.90 Posture: α = 0.62 |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
Nine inpatients completed the questionnaire on 2 occasions within 5 days apart (ICC 0.98; 95% CI 0.87–0.99) and 18 outpatients completing the questionnaire 24 hours apart (ICC 0.92; 95% CI 0.88 –0.95). |
| 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 | Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
Items selected after literature review, personal expert opinion and patients with ankylosing spondylitis input. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description |
Rash analysis was not performed in the original article. A subsequent article performing Rash analysis described better psychometric properties for the 0-48 global scale compared to the 0-3 global scale. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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