Table 2. Levels of evidence synthesis for methodological quality of paper and consistency of clinimetric evidence of measurement property.^a.

Level	Rating	Criteria
Strong evidence	+++ or—-	Consistent findings in multiple studies of good methodological quality OR in one study of excellent methodological quality
Moderate evidence	++ or —	Consistent findings in multiple studies of fair methodological quality OR in one study of good methodological quality
Limited evidence	+ or -	One study of fair methodological quality
Conflicting evidence	±	Conflicting findings
Unknown evidence	?	Only studies of poor methodological quality

+ = positive rating,— = negative rating, ± = conflicting rating,? = indeterminate rating

^aAdapted from Terwee et al., [7] Dobson et al. [31] and Dekkers et al. [20]