Quiz Item Analysis Report

The quiz item analysis report provides a break down of how multiple choice questions were answered and the total attempts on the multiple choice question.  For each multiple choice question the quiz item analysis report calculates the correct factor (Cor. Fac.), standard deviation (Std. Dev.), the discrimination index (Disc. Indx.), and the discriminative efficiency (Disc. Eff.).

Open

Calculations

% (Percentage)

The percentage of learners who selected the response.

Correct Factor

Correct Factor or % correct is a measure for a question’s the level of difficulty. The Correct Factor is calculated by finding the question's average number points achieved for learner using the mean. Then dividing the mean by the max possible points that can be earned for one learner, and the result is represented as a percentage.

Standard Deviation

Standard deviation is a measurement for how much the scores of the question vary.  The larger this value is the more the scores vary and the smaller the value the less the scores for the question vary.

This parameter is calculated by taking the variance and dividing it by the difference between the max and minimum possible score.  The result is then represented as a percentage.

Discrimination Index

The discrimination index is performance indicator for a question which determines how well a question differentiates between high and low performers. In the Quiz Analysis report the discrimination index is represented as a percentage. The discrimination index will range from 100% to -100%. The closer the discrimination index is to 100% the more the question distinguishes between the high and low performers, and the further away from 100% the less discriminating the question is between low and high performers. A negative discrimination index indicates that the question is being answered correctly by more of the lower performers than the higher performers. A question with very good discrimination will have a discrimination index between 40-100%.

Discrimination Efficiency

The discrimination efficiency provides an additional statistic that may be used to better interpret a question’s discrimination index.  The measurement attempts to assess how good the discrimination index is relative to the question’s difficulty. 

The weakness with the discriminative index is that if the percentage of learners who answered the question correctly is close to 0% or 100%, meaning that a majority of the learners answered the question incorrectly or correctly, the discrimination index will always be small.  The discrimination efficiency expresses the discrimination index as a fraction of the maximum possible value it could have taken given the scores the learners earned on the question and the entire test.