UNIDIMENSIONALITY OF A FUNCTIONAL MEASURE FOR PATIENTS WITH INJURED UPPER-LIMB

The construction of an instrument including a number of tests requires an analysis of its structure and its unidimensionality (which allows calculation of global score), and the determination of the difficulty level of various tests. This study examined a tool including 67 tests designed to evaluate the functional ability of patients with an injure d upper limb The patients seen in a rehabilitation centre during 12 mo nths (173 subjects) were evaluated by the occupational therapists fami liar with the tool. The statistical analyses were made using the princ ipal component analysis method (PCAM), the Cronbach's coefficient and the Rasch model. The PCAM showed 3 principal factors which explained 4 4 %, 10 % and 4 % of the total variance respectively in the case of pa tients with injured dominant limb. The predominance of the first axis and the high ratio of first by second eigenvalues suggested the unidim ensionality of the tool. The Cronbach's value of 0.97 attested the goo d congruence of the items. The results obtained with the Rasch model s eemed to be consistent with the hypothesis of the unidimensionality of the tool. This analysis also provided the difficulty scale of various tests. Similar results were obtained in patients with injured non dom inant limb or with all the sample. The methods used provide complement ary results.