Effects of stem orientation and completeness of multiple-choice items on item difficulty and discrimination

The effects of stem orientation (positively stated stem or negatively stated stem) and completeness (complete stem or incomplete stem) of multiple-choice items were studied experimentally. Provisions were also made for determining possible interactions between orientation, completeness, and achievement. Thus, subjects (142 senior education students) were classified into three achievement groups (Low, Medium, High). A three-way factorial design (orientation x completeness x achievement) was used as the experimental model. Results indicated that incomplete versus complete stems increased item difficulty but had no effect on discrimination. Stem orientation had no effect on either difficulty or discrimination. Neither orientation nor completeness interacted with achievement or with each other. The implications of the results are discussed.