Table 6.

Overall levels of evidence for the quality of the measurement properties

quality of evidence	rating	description
high	++++/−−−−	consistent findings in multiple studies of at least adequate quality OR in one study of very good quality
moderate	+++/−−−	consistent findings in multiple studies of at least doubtful quality OR in one study of adequate quality
low	++/−−	consistent findings in multiple studies of at least inadequate quality OR in one study of doubtful quality
very low	+/−	finding only from one study of doubtful quality
conflicting	±	conflicting findings
indeterminate	?	only studies of poor methodological quality