Date of Award


Document Type


Degree Name

Master of Arts (MA)




The investigation completed by Lipp (Evaluation of rehabilitation patients by direct estimation procedures, Ph.D. Dissertation, University of North Dakota, 1969) demonstrated that exceedingly reliable ratio scale measurement of degree of physical disability could be achieved by expert judges (Js) using direct estimation procedures.

In the present investigation, 10 J^s without formal rehabilitation training or experience made magnitude estimations of degree of physical disability shown by 10 rehabilitation patients in the modalities of ambulation and transfer. The patients' behaviors were depicted by the videotape recording which were used in the Lipp investigation. The magnitude estimation portion of the Lipp investigation was replicated except for the use of non-expert Js. The Js also made similarity estimations for the 45 pairs of patient-stimuli in the transfer modality.

Interjudge reliability for the magnitude estimation scales was highly significant (p<.001). Product-moment correlations between the magnitude estimation scales of non-experts and experts demonstrated extremely close correspondence (r = .999, r = .998). Judgmental variability was shown to increase with subjective magnitude as predicted by Ekman's law. A ratio scale was derived from the similarity estimations which corresponded closely to the magnitude estimation scales of experts and non-experts (r = .97). Cluster analyses of coefficients of similarity derived from the magnitude estimation scales and of the obtained similarity estimations resulted in clusters of patient-stimuli which were psychologically meaningful and which corresponded almost exactly to the clusters which Lipp obtained.

The discussion examined the usefulness of non-expert Js, the validity of their judgment, and the relationship of their judgment to that of experts.