INHIBITING BLIND GUESSING: THE EFFECT OF INSTRUCTIONS

Abstract

The idea of curbing blind guessing on multiple-choice items by the post hoc imposition of a penalty based on a proportion of incorrect answers has been in vogue for many years. Hamilton (1950) dates it back at least to 1920. He also points out its dubious theoretical footing. Another correction of similar vintage, although less often used, seeks to inhibit guessing by encouraging candidates to omit items about which they are totally at a loss. Recently, this approach has received fresh study (Traub & Hamilton, 1972; Waters & Waters, 1971). By awarding a score of 1/m for each item omitted, where m is the number of choices contained in the item, candidates are credited with the score they would presumably have obtained had they guessed blindly at the items they omitted. The operative word here is presumably. Lord (1975) has queried whether the instructions are always adequate and cites research by various workers, notably Slakter (1968), which concluded that examinees tended to omit items on which they could actually do better than chance. He also quotes studies by Mead and Smith (1957) and by Ebel (1968) which reported that when examinees felt completely uncertain of an answer, their forced responses to items they had omitted were little better than random. However, Lord noted that these studies used true-false items only and recommended that they should be repeated with multiple-choice items, stressing the importance of phrasing the instructions so as to bring about the desired effect among candidates. The study reported here falls into this category.