The incorrect response in multiple-choice examinations.

There are three causes for incorrect responses in multiple-choice question (MCQ) and true-false (T-F) tests: (i) guessing as a result of total ignorance; (ii) guessing as a result of partial knowledge; and (iii) so-called 'anti-knowledge', which we define as the recording of an incorrect response in the firm belief that it is the correct one. Anti-knowledge responses may have many causes: ambiguity about the words or implied meaning of a question, differences of scientific prejudice or opinion, or because of misconceptions. Whatever the cause, however, anti-knowledge always gives rise to a score which is less than the score obtained through random guessing. This is a major failing of the MCQ type of examination, and there is nothing that can be done about the scoring system to alleviate the problem. Essentially the type of question which might give rise to anti-knowledge responses has to be eliminated from the examination, thus ensuring that partial knowledge is always rewarded by a score equal to or greater than (but never less than) the score for random guessing.