Table 1 The interpretation of the psychometric properties

Reliability

Internal reliability

+

Cronbach’s ɑ or ICC ≥ 0.70

−

Cronbach’s ɑ or ICC < 0.70

Test/retest method

+

ICC ≥ 0.70 or Pearson correlation coefficient/ Spearman rank correlation coefficient ≥ 0.80

-

ICC < 0.70 or Pearson correlation coefficient/Spearman rank correlation coefficient < 0.80

Interrater reliability

+

ICC ≥ 0.70 or Pearson correlation coefficient/ Spearman rank correlation coefficient ≥ 0.80

−

ICC < 0.70 or Pearson correlation coefficient/Spearman rank correlation coefficient < 0.80

Validity

Content validity

+

The content of the assessment instrument is adequate, comprehensive, questions and tasks chosen to adequately reflect the content to be evaluated

-

Not all selected questions and tasks reflect the content, content is not relevant, comprehensive

Criterion validity

+

Significant and stable relation between measurement and another instrument (r ≥ 0.70) or with start/end measurement

−

Poor measurement correlation with another instrument (r < 0.70) or start / end measurement

Structural validity

+

Correlation with instruments measuring the same ≥ 0.50 or correlation higher for unrelated elements in the instrument than for unrelated ones

-

Correlation with instruments measuring the same < 0.50 or correlation with related elements in the instrument is lower than unrelated ones

Responsiveness

Responsiveness

+

Able to detect clinically significant changes over time

−

Cannot detect clinically significant changes over time