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试题的区分度,是表示某题区分不同水平考生的性能指标。某题的区分度,是以样本中不同学生得分的高低与该生实际水平高低之间的相关关系数γ的大小来表示的。在实际计算中,往往以全卷考试的总分作为反映学生实际水平的指标,即认为总分高的人,实际水平也高,反之亦然。据此,如果以 x_1表示某生该题之得分,y_1 为某生相应的总分,样本中的学生总数为 n,则该题的区分度可用公式
The degree of differentiation of the test questions is to indicate that a question distinguishes performance indicators of different levels of candidates. The degree of differentiation of a question is represented by the magnitude of the correlation between the scores of different students in the sample and the actual level of the student. In actual calculations, the total score of a full-volume examination is often used as an indicator reflecting the actual level of students. That is to say, the person with a higher total score is actually higher, and vice versa. Based on this, if x_1 represents the score of a certain student, y_1 is the corresponding total score of a student, and the total number of students in the sample is n, then the degree of differentiation of the question can be used formulae.