Table 4.

Level of evidence for psychometric quality for each measurement property based on Schellingerhout et al. (2011).

Level of evidence	Rating	Criteria based on appraisal of quality of methodology (rated according to COSMIN) and quality of findings (rated according to Table 3)
Strong evidence	+++ or −−−	Consistent findings across 2 or more studies of “good” methodological quality OR one study of “excellent” methodological quality
Moderate evidence	++ or −−	Consistent findings across 2 or more studies of “fair” methodological quality OR one study of “good” methodological quality
Weak evidence	+ or −	One study of “fair” methodological quality (examining convergent or discriminant validity if rating hypothesis testing)
Conflicting evidence	±	Conflicting findings across different studies (i.e., different studies with positive and negative findings)
Unknown	?	Only available studies are of “poor” methodological quality
Not Evaluated	NE	Only available studies are of “poor” methodological quality as rated on COSMIN

+, Positive result; –, Negative result.