Psychometric Properties Mobility Measures MS

Current study will investigate the quality (psychometric properties) and clinical utility of several mobility measures, according to disability level. Therefore, several aspects will be inquired: * Was there an effect of rehabilitation * Is the measure able to detect change over time? And thus the change exceed measurement error and is it clinically important (responsiveness) * Does the measure assess what it claims to measure (validity) * Is the measure able to differentiate all performances of the patients, inclusively the very good and very bad performances (floor and ceiling effects) * Does the measure gives similar results under consistent test conditions on another testing day (reliability) Worldwide, theoretical approaches to physical therapy and rehabilitation in Multiple Sclerosis often appear significantly different. Since the present research protocol will be performed at different centers across European countries (and US sites), this multi-center study can additionally be applied for mapping the volume and content of rehabilitation, as well as the differential impact of diverse rehabilitation approaches and training volume on mobility, for several disability levels. Some health-economic analyses will be performed to examine what the approximate cost of rehabilitation compared to effects is and what drivers of costs are (setting, equipment, staff).