Reliability of Strength Measures for the Dominant and Non-dominant Hands

The reliability of a measure refers to its degree of consistency or stability. Test-retest reliability involves administering the same test twice (Voyer, 1998). A perfectly reliable test would give the same results on both occasions. Intraclass correlation coefficients indicate the degree of reliability for continuous measures (Portney & Watkins, 2000). The reliability of grip strength measurements of hands needs to be ascertained so that therapists can determine if a change in grip strength is a real change due to intervention, disease resolution, or progression, or simply within the range of normal measurement error and physiological fluctuation. The reliability of measures of healthy hands needs to be determined before injured hands can be examined. This is because there are many more variables that impact upon injured hands such as fluctuating pain, medication levels, pathology and the psychological and physical responses of the individual to the injury, or disease.