Psychometric properties of the modified fatigue impact scale.

Psychometric assessments are tests or questionnaires that have been designed to measure constructs of interest in an individual or a target population. A goal of many of these self-report instruments is to provide researchers with the ability to gather subjective information in a manner that might allow for quantitative analysis and interpretation of these results. This requires the instrument of choice to have adequate psychometric properties of reliability and validity. Much research has been conducted on creating self-report quality of life questionnaires for individuals with multiple sclerosis (MS). This article focuses on one in particular, the Modified Fatigue Impact Scale (MFIS). The article starts with a brief description of the rationale, construction, and scoring of the inventory. Next, the best available reliability and validity data on the MFIS are presented. The article concludes with a brief discussion on the interpretation of scores, followed by suggestions for future research. This summative analysis is intended to examine whether the instrument is adequately measuring the impact of fatigue and whether the scores allow for meaningful interpretations.