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Table 2 COSMIN recommended criteria for good measurement properties

From: Measuring women’s experiences of maternity care: protocol for a systematic review of self-report survey instruments

Measurement property

Rating

Criteria

Structural validity

+

Classical Test Theory (CTT)

Confirmatory factor analysis: Comparative Fit Index or Tucker Lewis Index or comparable measure > 0.95 OR root mean square error of approximation < 0.06 OR standardised root mean residuals < 0.08

Item Response Theory (IRT)/Rasch

No violation of unidimensionality: Comparative Fit Index or Tucker Lewis Index or comparable measure > 0.95 OR root mean square error of approximation < 0.06 OR standardised root mean residuals < 0.08

AND

No violation of local independence: residual correlations among the items after controlling for the dominant factor < 0.20 OR Q3’s < 0.37

AND

No violation of monotonicity: adequate looking graphs OR item scalability > 0.30

AND

Adequate model fit:

IRT: χ2 > 0.001

Rasch: infit and outfit mean squares ≥ 0.5 and ≤ 1.5 OR Z-standardized values > − 2 and < 2

?

CTT: not all information for ‘+’ reported

IRT/Rasch: model fit not reported

Criteria for ‘+’ not met

Internal consistency

+

At least low evidence for sufficient structural validity AND Cronbach’s alpha(s) ≥ 0.70 for each unidimensional scale or subscale

?

Criteria for ‘At least low evidence for sufficient structural validity’ not met

At least low evidence for sufficient structural validity AND Cronbach’s alpha(s) < 0.70 for each unidimensional scale or subscale

Reliability

+

Interclass Correlation Coefficient (ICC) or weighted kappa ≥ 0.70

?

ICC or weighted kappa not reported

ICC or weighted kappa < 0.70

Measurement error

+

Smallest detectable change (SDC) or limits of agreement (LoA) < minimal important change (MIC)

?

MIC not defined

SDC or LoA > MIC

Hypotheses testing for construct validity

+

The result is in accordance with the hypothesis

?

No hypothesis defined (by the review team)

The result is not in accordance with the hypothesis

Cross-cultural validity/measurement invariance

+

No important differences found between group factors (e.g. age and language) in multiple group factor analysis OR no important differential item functioning (DIF) for group factors (McFadden’s R < 0.02)

?

No multiple group factor analysis OR DIF analysis performed

Important differences between group factors OR DIF was found

Criterion validity

+

Correlation with gold standard ≥ 0.70 OR area under the curve (AUC) ≥ 0.70

?

Not all information for ‘+’ reported

Correlation with gold standard < 0.70 OR AUC < 0.70

Responsiveness

+

The result is in accordance with the hypothesis OR AUC ≥ 0.70

?

No hypothesis defined (by the review team)

The result is not in accordance with the hypothesis OR AUC < 0.70