Purpose of Item Analysis • The process of examining the student’s responses to each item. • The need to look into the difficulty and discriminating ability of the item as well as the effectiveness of the each alternative.
Item Analysis Difficulty Index – the percentage of the student who got the item right. Can also be interpreted as how easy or how difficult an item is. Discrimination index – separates the bright students from the challenge ones.
Item Analysis • When we prepare test items we aim to have average difficulty • Item Analysis will help us in selecting the items that are of average difficulty.
Item Difficulty = number of students with correct answer/ total number of students Example: What is the item difficulty index of an item if 25 students are unable to answer it correctly while 75 answered it correctly? Item Difficulty = 75/100 = .75 or 75%
U-L Index Method (Santos, 2007) • Table of equivalents in interpreting the difficulty index Range of Difficulty Index Interpretation Action .00 to .25 Difficult Revise or discard .26 to .75 Right Difficulty Retain .76 & above Easy Revise or discard
Index of discrimination Difficulty Index = no. of students getting correct response/total = 40/100 = .40 or 40% within range of a good item DU=no. of students in upper 25% with correct response/no of students in the upper 25% = 15/20 = .75 or 75% DL=no. of students in lower 25% with correct response/no of students in the lower 25% = 5/20 = .25 or 25% Discrimination Index = DU-DL =.75-.25= .50 has a good discriminating power
U-L Index Method (Stocklein, 1957) • Table of equivalents in interpreting the difficulty index .00 to .20 – Very Difficult .21 to .80 – Moderately Difficult .81 to 1.00 – Very Easy