Difficulty Level Item Analysis 1. The Definition of Item Analysis

The discrimination index can range from -1 to +1, when a large proportion of students in the lower group got the item right more than those in the upper group, it discriminates negatively. 47 Item discriminating power can be obtained by subtracting the number of students in the lower group who got the item right U from the number of students in the upper group who got the item right L and dividing by the total number of students in one group included in the item analysis N. Discrimination index is symbolized in D or DP Discrimination Power. To count the discriminating power, the formula is as below: DP = Correct U – Correct L n Explanation: DP: Discriminating Power U : Sum of the students from the upper group who answered correctly L : Sum of the students from the lower group who answered correctly N : Number of the candidates in one group The result is interpreted by using the criteria : If DP is 0,20 to 1,00 = Good satisfactory, good and excellent ≤ 0.20 = Revise poor Negative value on D = Discard or rewrite very poor. 48 Stated by Sumarna, summarized in formula form, as below: DI = U – L N Where: DI = the index of discriminating power U = the number of pupils in the upper group who answered the item correctly 47 Sumarna Surapranata, Analisis, Validitas, Reliabilitas dan Interpretasi Hasil Tes “Implementasi Kurikulum 2004”, Bandung: PT. Remaja Rosdakarya, 2006, p. 23. 48 Sudijono, op.cit., p. 408. L = the number of pupils in the lower group who answered the item correctly N = number of pupils in each of the groups. 49 The classifications of the index of discriminating power D are: DI = 0.07 – 1.00 = Excellent 0.40 – 0.70 = Good 0.20 – 0.40 = Satisfactory ≤ 0.20 = Poor Negative value on D = Very Poor. 50 By using the formula of DP and the criteria above, teachers can select the items which are fulfilled to that standardizations or not, so hehe can determine to use, revise or skip the item for the future. In this skripsi, the writer is focusing on testing procedure. Acoording to explanation above, there are two kinds of achievement tests which are held periodically, they are progress and the final test. 49 Surapranata, op. cit., p. 31. 50 Ibid., p. 389.