THE MULTIDIMENSIONAL FATIGUE INVENTORY (MFI) PSYCHOMETRIC QUALITIES OF AN INSTRUMENT TO ASSESS FATIGUE

The Multidimensional Fatigue Inventory (MFI) is a 20-item self-report instrument designed to measure fatigue. It covers the following dimens ions: General Fatigue, Physical Fatigue, Mental Fatigue, Reduced Motiv ation and Reduced Activity. This new instrument was tested for its psy chometric properties in cancer patients receiving radiotherapy, patien ts with the chronic fatigue syndrome, psychology students, medical stu dents, army recruits and junior physicians. We determined the dimensio nal structure using confirmatory factor analyses (LISREL's unweighted least squares method). The hypothesized five-factor model appeared to fit the data in all samples tested (AGFIs>0.93). The instrument was fo und to have good internal consistency, with an average Cronbach's alph a coefficient of 0.84. Construct validity was established after compar isons between and within groups, assuming differences in fatigue based on differences in circumstances and/or activity level. Convergent val idity was investigated by correlating the MFI-scales with a Visual Ana logue Scale measuring fatigue (0.22<r<0.78). Results, by and large, su pport the validity of the MFI.