Improved Overlapping Methods for Determining Validities of Test Items

niques for determining validities of test j items is the Vincent Overlapping method.1 By this method the validity value for any item is the per cent of those failing the I item who have higher criterion scores than | the median criterion score of those who pass the item. Consider, for example, a test | administered to 100 students, with 30 fail ing a particular item. If, of these 30, 6 have criterion scores higher than the median ? score of the 70 who get the item correct, the Vincent validity value for the item will be 6/30 of 100, or 20. The smaller this j measure of overlapping the greater is the I discriminating power of the item, and so the higher is its validity. Usually the critei rion score is simply the total score on the test of which the item forms a part. j The Vincent method makes rather inade