Discrimination: Indicates how well a question differentiates between students who know the subject matter and those who don't. A question is a good discriminator when students who answer the question correctly also do well on the test. Values can range from -1.0 to +1.0.
How to Run an Item Analysis on a Test:Go to one of the previously listed locations to access item analysis (see above).Access the test's contextual menu from the downward facing chevron on its right.Select Item Analysis.In the Select Test drop down list, select a test. ... Click Run.More items...
Determine the Discrimination Index by subtracting the number of students in the lower group who got the item correct from the number of students in the upper group who got the item correct. Then, divide by the number of students in each group (in this case, there are five in each group).
The discrimination index (DI) measures how discriminating items in an exam are – i.e. how well an item can differentiate between good candidates and less able ones. For each item it is a measure based on the comparison of performance between stronger and weaker candidates in the exam as a whole.
When the discrimination index is negative it means that the examinees in the low performing group got the answer correct at a higher rate than the higher performing group.
0:199:01Item Analysis - YouTubeYouTubeStart of suggested clipEnd of suggested clipFirst we rank the scores of the students from highest to lowest score. Second we select and identifyMoreFirst we rank the scores of the students from highest to lowest score. Second we select and identify the top 27 percent performing tube and the bottom 27 performing from the total takers.
The closer the difficulty of an item approaches to zero, the more difficult that item is. The discrimination index of an item is the ability to distinguish high and low scoring learners. The closer this value is to 1, the better the item distinguishes the learners who get a high score from those who get a low score.
The discriminant is the part of the quadratic formula underneath the square root symbol: b²-4ac. The discriminant tells us whether there are two solutions, one solution, or no solutions.
Item analyses are intended to assess and improve the reliability of your tests. If test reliability is low, test validity will necessarily also be low. This is the ultimate reason you do item analyses—to improve the validity of a test by improving its reliability.
Count the total number of students answering each item correctly. For each item, divide the number answering correctly by the total number of students. This gives you the proportion of students who answered each item correctly. This figure is called the item's difficulty level.Jan 30, 2019