A Note on the Validity and Difficulty of Items in form a of the Otis Self-Administering Tests of Mental Ability

Abstract

Although the Otis Self-Administering Test of Mental Ability (i) is widely used, there seems to be no published data concerning spe cific item validities of the test. purpose of this study was to obtain measures of the validity and difficulty of test items in Form A of the higher examination of this test based on a group different from that on which the orig inal item validities were established. As a matter of interest, these were computed sep arately for the sexes in order to note whether there might be any significant sex differences in the validity or difficulty of test items. Otis (2; Pg. 3) states that the items were originally validated on about 1000 high school students and 1000 grammar school pupils . subjects in the present study were 100 men and 100 women who had taken the test in connection with an other investigation. group of 100 women had a mean Otis I. Q. of 108 with the ex tremes at 72 and 140. Ages varied from 18 to 33. group of men had a mean Otis L Q. of in with a range of 72 to 135. Ages varied from 18 to 32 with three exceptions? one 36, one 37, and one 52. mean age was 25. Concerning the original validation, Otis states (2; Pg. 3): students were divided in each case into two groups, a 'good group' and a 'poor group'. same number were taken from each grade from both groups. good group constituted the young students, and the poor group the old students. These groups had reached the same average edu cational status, therefore, but at different rates. Now it is the rate at which a stu dent can progress through school that the mental-ability test is chiefly used to pre dict. Therefore this is believed to be the best criterion by which to judge the valid ity of each item that goes into the test. number of times each item was passed bv each group was then found and only those items chosen which showed a distinct gain in number of passes by the good group over the number of passes by the poor group in spite of the fact that the median age of the good group was over two years less than that of the poor group. Each item justified its inclusion, therefore, be cause it distinguished between students who progressed slowly and those who progressed rapidly. The items in each form of each exam ination have been arranged in the order of difficulty, according to the number of passes of each item by the students taking the preliminary editions.