Comparison of psychometric measures of fatigue

Many psychometric instruments have been developed to measure various components of fatigue. In this study the factor structure of the scales included in nine psychometric instruments developed to measure different components of fatigue were investigated. One hundred and thirty-four research participants completed the nine instruments in groups of approximately 30 each. Factor analysis of the scores obtained on these scales yielded a two-factor solution with 11 scales loading 0.40 or greater on the first factor and 10 scales loading 0.40 or greater on the second factor. These two factors, Distress-Fatigue and Vigor, accounted for 48 percent of the total variance and approximated simple structure. The results reveal that the different psychometric measures of fatigue are really measuring only two different factors rather than the many different factors specified by the different instruments.