To discourage guessing on multiple-choice tests, formula scoring, such as R – W/3 (where R is the number right and W is the number wrong for a four-option item), is often employed. This method penalizes incorrect answers, making it less advantageous to guess randomly. In contrast to 'number right' scoring, where only correct answers contribute positively to the score and incorrect answers have no penalty, formula scoring subtracts points for wrong responses.
The rationale behind this approach is to adjust for the expected number of correct answers that would occur purely by chance. By penalizing incorrect answers, test-takers are incentivized to only answer questions they have a reasonable degree of confidence in, rather than guessing blindly. This aims to provide a more accurate reflection of a student's actual knowledge by reducing the impact of random chance on their score, thereby encouraging more thoughtful engagement with each question.