Analyze Bubble Sheet Questions in Gradescope

Gradescope's Item Analysis Report provides question-level performance data, including answer distributions, difficulty ratings, and discrimination scores. Instructors can investigate flagged questions and adjust grading when necessary to improve assessment accuracy.

Quick Links: | Prerequisites | Instructions | Troubleshooting | 

Introduction

Gradescope's Item Analysis Report helps instructors evaluate how students performed on individual bubble sheet questions. The report displays response distributions, question difficulty, and discrimination scores that indicate how well certain questions distinguish between higher- and lower-performing students. Gradescope automatically flags questions with low discrimination scores for further review. These insights can help instructors identify unclear questions, assess potential issues with the answer key, and improve future assessments.

Prerequisites

• Instructor access to Gradescope.
• A graded bubble sheet assignment.
• Questions configured with Exact Scoring to generate discrimination scores.

Step-by-Step Instructions

Analyze Bubble Sheet Question Performance

Review the Item Analysis Report

To review individual question performance in Gradescope, do the following:

1. Open the bubble sheet assignment in Gradescope.
2. Navigate to Item Analysis.
3. Review the list of questions and available answer options.
4. Examine the percentage of students who selected each answer.
5. Identify answers displayed in green, which indicate correct responses.
6. Review percentages displayed in red, which indicate that an incorrect answer was selected by more students than the correct answer.
7. Identify questions that may require further investigation.

The report helps instructors determine whether students consistently misunderstood particular questions or selected unexpected answers.

Interpret Discrimination Scores

Gradescope uses the point-biserial correlation coefficient to calculate discrimination scores for questions using Exact Scoring.

A discrimination score measures the relationship between answering a question correctly and performing well on the assignment overall.

Discrimination score	Interpretation
Below 0.20	Flagged by Gradescope for possible review.
0.20 or higher	Not automatically flagged by Gradescope's low-discrimination threshold.
N/A	Cannot be calculated because all students answered correctly or all students answered incorrectly.

A discrimination score below 0.20 may indicate that a question does not effectively distinguish between higher- and lower-performing students.

Possible explanations include unusually easy or difficult questions, ambiguous wording, or potentially incorrect answer keys.

A low discrimination score does not automatically mean a question is invalid.

Investigate Flagged Questions

Gradescope automatically flags questions with discrimination scores below 0.20 in the Insights panel.

To investigate flagged questions, do the following:

1. Navigate to Item Analysis.
2. Locate the Insights panel.
3. Select a flagged question.
4. Review its question difficulty classification.
5. Compare the performance of the highest-scoring 27% of students with the lowest-scoring 27%.
6. Determine whether the question warrants an adjustment to its wording, answer key, or grading rubric.

Gradescope classifies question difficulty based on the percentage of students who answered correctly.

Classification	Percentage answered correctly
Hard	Less than 50%
Medium	50%–84%
Easy	85%–100%

These classifications help instructors identify questions that may have been unexpectedly challenging or easy for students.

Adjust Questions or Scoring

If the analysis identifies a possible grading issue, instructors can review the affected question's rubric or the assignment's answer key.

To adjust grading after reviewing the item analysis, do the following:

1. Select the affected question from Item Analysis.
2. Access the question's grading rubric or the assignment's answer key.
3. Review the correct answer and existing scoring rules.
4. Make necessary adjustments.
5. Return to Item Analysis to review the updated results, if applicable.

Changes to rubric items can affect scores for students assigned those items, so verify the impact of any grading adjustment.

Troubleshooting

If a discrimination score displays N/A, verify whether every student answered the question correctly or incorrectly. Gradescope cannot calculate the discrimination score in either situation.

If a question does not display a discrimination score, confirm that it uses Exact Scoring. Other scoring styles may not support this calculation.

If a question has a low discrimination score, review its difficulty, wording, answer options, and overall assessment context before changing grades.

For additional information, see Gradescope's Grading a Bubble Sheet Assignment guide and Creating a Bubble Sheet Assignment