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Table 3 Quality criteria for measurement properties [Based on Terwee et al., [17]]

From: Measurement properties of translated versions of neck-specific questionnaires: a systematic review

Property Rating Quality Criteria
Reliability   
Internal consistency + (Sub)scale unidimensional AND Cronbach's alpha(s) ≥ 0.70
  ? Dimensionality not known OR Cronbach's alpha not determined
  - (Sub)scale not unidimensional OR Cronbach's alpha(s) < 0.70
Measurement error + MIC > SDC OR MIC outside the LOA
  ? MIC not defined
  - MIC ≤ SDC OR MIC equals or inside LOA
Reliability + ICC/weighted Kappa ≥ 0.70 OR Pearson's r ≥ 0.80
  ? Neither ICC/weighted Kappa, nor Pearson's r determined
  - ICC/weighted Kappa < 0.70 OR Pearson's r < 0.80
Validity   
Content validity + The target population considers all items in the questionnaire to be relevant
   AND considers the questionnaire to be complete
  ? No target population involvement
  - The target population considers items in the questionnaire to be irrelevant
   OR considers the questionnaire to be incomplete
Construct validity   
- Cross-cultural validity + Original factor structure confirmed OR no important DIF
  ? Confirmation original factor structure AND DIF not mentioned
  - Original factor structure not confirmed OR important DIF
- Structural validity + Factors should explain at least 50% of the variance
  ? Explained variance not mentioned
  - Factors explain < 50% of the variance
- Hypothesis testing + (Correlation with an instrument measuring the same construct ≥ 0.50 OR
   at least 75% of the results are in accordance with the hypotheses) AND
   correlation with related constructs is higher than with unrelated constructs
  ? Solely correlations determined with unrelated constructs
  - Correlation with an instrument measuring the same construct < 0.50 OR
   < 75% of the results are in accordance with the hypotheses OR
   correlation with related constructs is lower than with unrelated constructs
Responsiveness   
Responsiveness + (Correlation with an instrument measuring the same construct ≥ 0.50
   OR at least 75% of the results are in accordance with the hypotheses
   OR AUC ≥ 0.70) AND correlation with related constructs is higher
   than with unrelated constructs
  ? Solely correlations determined with unrelated constructs
  - Correlation with an instrument measuring the same construct < 0.50 OR
   < 75% of the results are in accordance with the hypotheses OR AUC < 0.70
   OR correlation with related constructs is lower than with unrelated constructs
  1. [..] = reference number, MIC = minimal important change, SDC = smallest detectable change, LOA = limits of agreement, ICC = intraclass correlation coefficient, DIF = differential item functioning, AUC = area under the curve
  2. + = positive rating, ? = indeterminate rating, - = negative rating