1. Scientific and clinical problems in indexes of functional disability;Feinstein;Ann Int Med,1986
2. Functional assessment measures in medical rehabilitation: current status;Keith;Arch Phys Med Rehabil,1984
3. Ordinal scales and foundations of misinference;Merbitz;Arch Phys Med Rehabil,1989
4. Observations are always ordinal: measurements, however, must be interval;Wright;Arch Phys Med Rehabil,1989
5. Probabilistic models for some intelligence and attainment tests;Rasch,1980