Effect of Two Selected Item-Writing Practices on Test Difficulty, Discrimination, and Reliability

In order to investigate the effect of two item-writing practices on test characteristics, examinations were chosen for study in two undergraduate courses (N = 71 and 210) . About one-fourth of the items on each examination included a practice generally regarded as undesirable in measurement textbooks and alleged to make test items more difficult. Alternate forms which eliminated the undesirable practice were developed and administered at the same time as the original form. Rewriting item stems so that they formed a complete sentence or question resulted in about 6 percent more students answering items correctly. Eliminating unnecessary material in item stems, however, had little effect on difficulty. KR 20 values were not appreciably different for the two versions of either test. Neither flaw was found to affect item discrimination indices noticeably. The absence of any substantial practice-by-achievement level interactions suggested little effect of the practices on the validity of the tests.