This calculator allows you to determine the item difficulty and discrimination indexes based on a set of test item responses.
Item difficulty and discrimination are two important indicators of test quality and item performance. Item difficulty measures how easy or hard an item is for the test takers, based on the proportion of correct responses. Item discrimination measures how well an item distinguishes between the high and low achievers, based on the difference between the proportions of correct responses in the high and low groups. These indicators can help test developers and instructors evaluate the effectiveness of their tests and items, and make necessary revisions or improvements.
To interpret the item difficulty and discrimination values, some cutoff points can be used as guidelines. For item difficulty, a standard range is 0.25 to 0.75, with a higher value indicating an easier item12. For item discrimination, an acceptable value is 0.2 or higher, with a higher value indicating a better discriminating item. However, these cutoff points may vary depending on the context and purpose of the test.
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