Background / aim: Using reliable outcome measures is a necessity for the occupational
therapy profession in enabling valid assessments of clients. Although Cronbach’s alpha is the
most widely applied index of internal consistency reliability, there are misconceptions about
its use and interpretation. This paper aims to guide assessment developers in paediatric
occupational therapy, as well as practitioners who are evaluating outcome measures in using
and interpreting the Cronbach’s alpha estimates appropriately. This will enable them to decide
on the tools’ clinical value and incorporate them into their practice with children.
Method: Previously published papers reporting on internal consistency issues of outcome
measures in paediatric occupational therapy were searched through the Allied and
Complementary Medicine database. These papers were used as a basis to discuss possible
reasons for reporting of low internal consistency.
Results: The analysis demonstrates that Cronbach’s alpha reports are not always interpreted
in a sound way. The paper emphasises that one should be cautious about judging estimates of
internal consistency. Low size of the coefficient alpha might not always indicate problems
with the construction of the tool; whereas large sizes do not always suggest adequate
reliability. Instead, these reports might be related to the data characteristics of the construct.
Conclusion: In judging an outcome measure’s internal consistency , researchers and
practitioners in occupational therapy should report and consider the nature of data, the scale’s
length and width, the linearity and the normality of response distribution, the central response
tendency, the sample response variability and the sample size
