Vocabulary: Item Difficulty

Item Difficulty is a number we evaluate based on a relative comparison to a larger population. Depending on whether the item is multiple choice or scored on a rubric, item difficulty is slightly different.

Multiple Choice Item Difficulty is a comparison of how students in one district performed against students in a larger population. Item Difficulty should not be judged until a comparison is made. For example, 55% of students in District X got Multiple Choice Item 1 correct, but only 51% of students in BOCES and 52% of students in All Districts got it correct then it was a relatively difficult item overall. However if 80% of students in BOCES and All Districts scored this item correct, then it was a relatively easy item overall, but a particularly difficult item for students in District X.

Cluster Items and Rubric Items Item Difficulty is not simply the number of students who scored correct on a given rubric item. Rather it is a percentage of the total points scored out of the total points possible. For example, if a rubric item is worth 3 points and 100 students responded, then the points possible would be 300 (3*100). The points earned adds up all of the points of all 100 students into one big number. In this example we will state that students in District X earned 200 points. The Item Difficulty is calculated by taking the points earned, dividing it by the points possible, and multiplying by 100 ((200/300)*100). In this case the percentage would be approximately 67%.