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Table 3 Adequacy criteria for measurement properties adapted from [21] and [27]

From: Measurement properties of quality of life measurement instruments for infants, children and adolescents with eczema: protocol for a systematic review

Property Rating Adequacy criteria
Reliability   
Internal consistency (CTT methods applied) + Cronbach’s alpha(s) ≥0.70
? Cronbach’s alpha not determined
Cronbach’s alpha(s) <0.70
Internal consistency (IRT methods applied) + Person Separation Index ≥0.70
? Person Separation Index not determined
Person Separation Index <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 + All items are considered to be relevant for the construct to be measured, for the target population, and for the purpose of the measurement AND the questionnaire is considered to be comprehensive
? Not enough information available
Not all items are considered to be relevant for the construct to be measured, for the target population, and for the purpose of the measurement OR the questionnaire is considered not to be comprehensive
Construct validity   
Structural validity (CTT methods applied) + Factors should explain at least 50 % of the variance
? Explained variance not mentioned
Factors explain <50 % of the variance
Structural validity (IRT methods applied) + Residual correlations among the items after controlling for the dominant factor <0.20 OR Q3’s <0.37, item scalability >0.30, IRT model fit: G2 >0.01, no DIF for important subject characteristics (such as age, gender, education): McFadden’s R 2 <0.02, OR no non-uniform DIF
? Important statistics not reported
Residual correlations among the items after controlling for the dominant factor ≥0.20 OR Q3’s ≥0.37, item scalability ≤0.30, IRT model fit: G2 ≤0.01, important DIF for important subject characteristics (such as age, gender, education): McFadden’s R 2 ≥0.02, OR non-uniform DIF
Hypothesis testing (convergent/divergent validity) + Correlations with instruments 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
Correlations with instruments 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
Hypothesis testing (discriminative validity) + Differences in scores on the measurement instrument for all evaluated patient subgroups are statistically significant OR ≥75 % of results in accordance with hypotheses
? Some differences statistically significant, others not
Differences in scores on the measurement instrument for all evaluated patient subgroups are not statistically significant OR <75 % of results in accordance with hypotheses
Cross-cultural validity + No differences in factor structure OR no important DIF between language versions
? Multiple group factor analysis not applied AND DIF not assessed
Differences in factor structure OR important DIF between language versions
Responsiveness   
Responsiveness + Correlation with changes on instruments measuring the same construct ≥0.50 OR at least 75 % of the results are in accordance with the hypotheses OR AUC ≥0.70 AND correlations with changes in related constructs are higher than with unrelated constructs
? Solely correlations determined with unrelated constructs
Correlations with changes on instruments measuring the same construct <0.50 OR <75 % of the results are in accordance with the hypotheses OR AUC <0.70 OR correlations with changes in related constructs are lower than with unrelated constructs
  1. MIC minimal important change, SDC smallest detectable change, LoA limits of agreement, ICC intraclass correlation coefficient, AUC area under the curve, + positive rating, ? indeterminate rating, − negative rating