Purpose of The Item Analysis

30 measure the difficulty level and discriminating power of each test item, and then analyzed the difficulty level and discriminating power of each test item. She adopted the following formula to find out the difficulty level of each item in the last examinations English summative test for Junior High School level at SMP Islam Annur Tanah Abang Jakarta Barat academic year 2013-2014: DL : The index of difficulty level U : The number of students in the upper group who answered the item correctly L : The number of students in the lower group who answered the item correctly T :Total number of students in upper and lower group 1 To find out the difficulty level of all items in the last examinations English summative Test for Junior High School academic year 2013-2014, she used the following formula: P : Difficulty level of all items B : Difficulty level of each items ∑ : Sigma total N : Total number of the test item 1 Ngalim Purwanto, prinsip-prinsip teknik evaluasi pengajaran, Bandung Remaja Rosdakarya, 1986, p. 119. DL = U + L T P = ∑b N 31 Table 3.1 The range of the difficulty level 2 : P Interpretation ≤ 0.30 Difficult 0.31 – 0.69 Moderate ≥ 0.70 Easy This lists students score from those who get the highest to those who got the lowest. She classified the students based on their scores. The purpose was to make it easier to divide these students into three group of each category of test type, namely Upper Group UG, Middle Group MG, and Lower Group LG 3 . To do the analysis of difficulty level, the groups analyzed were the UG and the LG only. And then, she tabulated the result of classifying students to those groups into table. To know the difficulty level of all items, she implemented the formula above. Firstly, she counted the total number of students in the upper group who answered the item correctly and the number of students in the lower group who answered the item correctly and then divide by the total number of students in upper and lower group to get the index difficulty of each item. And then, the result of index difficulty level of each item was divided by the total number of the test item to get the index difficulty of all items. Next, to do analysis of the discriminating power of test was an index that shows its ability to differentiate between pupils who have achieved well the upper group and those who have achieved poorly The lower group. Probably the most popular method of calculating an index of item discrimination is based on the difference between those who score well on the overall test and those who score poorly. 2 Sumarna, Surapranata, Analisis, Validitas, Reliabilitas, danInterpretasiHasil Test, Bandung: Remaja Rosdakarya, 2006, p. 21. 3 Sumarna, Surapranata, op.cit., p. 23. 32 From the statements, the writer can conclude that the discrimination index distinguishes for each item between the performance of students who do well on the exam and students who do poorly. The Discriminating Power was calculated by using formula: Where, D = Discrimination Index N = Number of candidates in one group U = Upper half L = Lower half After the calculation has been done, it can be seen whether the item has good discrimination power or not with the classification as follow. D= Correct U - Correct L N 0.70-1.00 = Excellent 0.40-0.70 = Good 0.20 – 0.40 = Satisfactory 0.20 = Poor Negative - = Discarded