| MEASUREMENT PROPERTIES | |
| Limitations | >=5 European languages (English) |
| Observations | |
| 1. RELIABILITY | |
| A. Internal Consistency | Tested |
| Cronbach's (Describe) |
High Cronbach's α scores of 0.70 to 0.96 show good internal consistency |
| B. Reliability intraobserver or test-retest | Tested |
| Continuous scores: intraclass correlation coefficient (ICC) Dichotomus: Cohen kappa (Describe) |
A systematic review published in 2009 analyzed 41 studies that examined at least one aspect of the psychometric properties of the NDI. A high test‐retest reliability was demonstrated in populations with both acute and chronic neck pain, with a reliability coefficient of more than 0.90 in most studies |
| 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 | Not Tested |
| Expert opinion (relevance and comprehensiveness) (Describe) |
|
| B. Construct Validity: Structural validity |
Not Tested |
| Hypotheses-testing | Tested |
| Cross-cultural validity | Not Tested |
| Brief Description | |
| C. Criterion validity | Tested |
| Comparison with a 'gold standard' Continuous scores: correlations, ROC curves Dichotomus: Sensitivity & Specificity (Describe) |
The NDI was originally developed in English but has been culturally adapted and translated into several languages including German, Spanish, Arabic, Chinese , Turkish, Japanese Polish. Finnish, Greek, Portuguese, and other languages |