| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations |
Authorized versions of the questionnaire are available in several languages. These can be obtained under the same conditions (by contacting the developers). |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
Cronbach’s alpha for most subscales ranged from 0.85–0.89 (in patients with RA or primary Sjogren syndrom, PSS) |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
In AS and PSS: ICC= 0.57–0.85 across the subscales. In patients with chronic widespread pain or FMS: ICC=0.75–0.92. |
| 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) |
The 5 fatigue domains were generated from 24 draft items developed from existing literature and in-depth interviews with patients with cancer. For each of these 5 domains, experts tried to create brief, positively and negatively phrased items that exclude somatic issues. |
| B. Construct Validity: Structural validity |
Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Tested |
| Brief Description |
Factor analysis on the 24 items supported the 5 subscales with adjusted goodness of fit index ranging from 0.95 to 0.98. |
| C. Criterion validity | Not Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
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