THE TVERSKY CONDITION APPLIED TO RATING-SCALES

This study is the first empirical investigation of the 1964 Tversky co ndition applied to rating scales. The Tversky condition posits that th e 3-response format will be optimum if testing time is proportional to the length of the test. To this end, 2-, 3-, 4-, and 5-response categ ory forms of a 10-item measure of attitudes in science were randomly a dministered to 241 third grade students. Reliability and validity were computed for each form. No significant differences were found among t he reliability coefficients or among the validity coefficients. The Tv ersky condition was not confirmed for rating scales. These findings ar e consistent with results from other studies regarding the lack of sub stantial differences among reliability and validity coefficients as th e number of response categories in a rating scale are varied.