Development of a measure of perceived functional ability.

The intra-test and test-retest reliability of the Spinal Function Sort was assessed in a multisite study involving 180 disabled subjects. The results of this study demonstrate the reliability of the instrument across a variety of sites. In addition, this study demonstrated both differences in absolute scores and a pattern of reactivity to the instrument that suggests that perceived functional ability may be affected by the subject's degree of chronicity measured in terms of the time that elapsed between date of injury and datae of testing.