Note: The question statistics table provides item analysis statistics for each question in the test. Questions that are recommended for your review are indicated with red circles so that you can quickly scan for questions that might need revision.
In general, good questions have:
- Medium (30% to 80%) difficulty.
- Good or Fair (greater than 0.1) discrimination values.
Questions that are recommended for review are indicated with red circles. They may be of low quality or scored incorrectly. In general, questions recommended for review have:
- Easy ( > 80%) or Hard ( < 30%) difficulty.
- Poor ( < 0.1) discrimination values.
- Filter the question table by question type, discrimination category, and difficulty category.
- Investigate a specific question by clicking its title and reviewing its Question Details page.
- Statistics for each question are displayed in the table, including:
- Discrimination: Indicates how well a question differentiates between students who know the subject matter those who do not. 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. Questions are flagged for review if their discrimination value is less than 0.1 or is negative. Discrimination values cannot be calculated when the question's difficulty score is 100% or when all students receive the same score on a question.
- For more information on how Blackboard calculates the discrimination values see Blackboard's Item Analysis.
- Difficulty: The percentage of students who answered the question correctly. Difficulty values can range from 0% to 100%, with a high percentage indicating that the question was easy. Questions in the Easy (greater than 80%) or Hard (less than 30%) categories are flagged for review. Difficulty levels that are slightly higher than midway between chance and perfect scores do a better job differentiating students who know the tested material from those who do not. It is important to note that high difficulty values do not assure high levels of discrimination.
- Graded Attempts: Number of question attempts where grading is complete. Higher numbers of graded attempt produce more reliable calculated statistics.
- Average Score: Scores denoted with an * indicate that some attempts are not graded and that the average score might change after all attempts are graded. The score displayed here is the average score reported for the test in the Grade Center.
- Standard Deviation: Measure of how far the scores deviate from the average score. If the scores are tightly grouped, with most of the values being close to the average, the standard deviation is small. If the data set is widely dispersed, with values far from the average, the standard deviation is larger.
- Standard Error: An estimate of the amount of variability in a student's score due to chance. The smaller the standard error of measurement, the more accurate the measurement provided by the test question.