The effect of misinformation, partial information, and guessing on expected multiple-choice test item scores

Six response/scoring methods for multiple-choice tests are analyzed with respect to expected item scores under various levels of information and misinformation. It is shown that misinformation always and necessarily results in expected item scores lower than those associated with complete ignorance. Moreover, it is shown that some response/ scoring methods penalize all conditions of misinformation equally, and others have varying penalties according to the number of wrong choices the misinformed examinee has categorized with the correct choice. One method exacts the greatest penalty when a specific wrong choice is believed correct ; two other methods provide the maximum penalty when the examinee is confident only that the correct choice is incorrect. Partial information is shown to yield substantially different expected item scores from one method to another. Guessing is analyzed under the assumption that examinees guess whenever it is advantageous to do so under the scoring method used and that these conditions would be made clear to the examinee. Additional guessing is shown to have no effect on expected item scores in some cases, though in others it is shown to lower the expected item score. These outcomes are discussed with respect to validity and reliability of resulting total scores and also with respect to test content and examinee characteristics