《英语测试学课件》scores analysisi II

1、To determine the difficulty level of test items, a measure called the Difficulty Index is used.、This measure asks teachers to calculate the proportion of students who answered the test item accurately. For example, lets say you gave a multiple choice quiz and there were four answer choices (A, B, C,

2、 and D). The following table illustrates how many students selected each answer choice for Question #1 and #2.If the difficulty is below .25, it is a difficult item. Given these parameters, this item could be regarded moderately easy - lots (80%) of students got it correct. In contrast, Question #2

3、is much more difficult (12/30 = .40). In fact, on Question #2, more students selected an incorrect answer (B) than selected the correct answer (A). This item should be carefully analyzed to ensure that B is an appropriate distractor. Facilityty value/ the item difficulty index难易度指数The item difficult

4、y index is one of the most useful, and most frequently reported, item analysis statistics. R NFV=faculty valueR= the number of students who have right answer.N=the total number of students who attended the testFV=The range of FV is : 0 FV 1.It can range between 0.0 and 1.0, with a higher value indicating that a greater proportion of examinees responded to the item correctly, and it was thus an easier item.If FV=0, it means that the item in the test is the most difficult. (no students can give the right answer)If FV=1, it means it means that