Difficulty & Discrimination Index of a Google Form Test // 172 Respondents // 50 MCQ Item Analysis

Introduction

In this tutorial, we will analyze a Google Form exam using two important metrics: the difficulty index and the discrimination index. This analysis helps educators understand how well their test items perform and how effectively they differentiate between high and low-performing students. We will guide you through each step of the process, ensuring you can apply these concepts to your assessments.

Step 1: Arrange Scores from Highest to Lowest

To begin your item analysis, you need to organize the scores of all respondents.

• Collect all the test scores from your Google Form.
• Use a spreadsheet application (like Excel or Google Sheets) to input the scores.
• Sort the scores in descending order, from highest to lowest.

Practical Tip: Ensure that you have all scores accurately recorded to avoid errors in subsequent steps.

Step 2: Identify Top and Bottom Groups

Next, you will determine the top and bottom groups of examinees.

• Calculate the total number of respondents (in this case, 172).
• Identify the top 27% and the bottom 27% of respondents:
  • Top group: 27% of 172 ≈ 46 respondents.
  • Bottom group: 27% of 172 ≈ 46 respondents.
• Select the top 46 and bottom 46 scores from your sorted list.

Common Pitfall: Make sure to round numbers appropriately. Always verify that your groups are of equal size.

Step 3: Count Correct Responses

Now, you will analyze how each group performed on the test items.

• For each multiple-choice question (MCQ), count how many respondents in the top group answered correctly.
• Do the same for the bottom group.

Practical Tip: Keep a tally for each question, as this will make calculations easier in the next steps.

Step 4: Compute the Difficulty Index

With your counts ready, it's time to calculate the difficulty index for each question.

• The formula for the difficulty index (P) is:

  P = (Number of correct answers) / (Total number of responses)
  

• Use this formula for both the top and bottom groups to determine how difficult each question was.

Real-World Application: A lower difficulty index indicates a question was too hard, while a higher index suggests it was easier.

Step 5: Compute the Discrimination Index

Next, you will assess how well each question differentiates between high and low performers.

• The formula for the discrimination index (D) is:

  D = (Number of correct answers in the top group - Number of correct answers in the bottom group) / (Total number of respondents in each group)
  

• Calculate this for each question to see how effectively it discriminates between the two groups.

Common Pitfall: Be attentive to the results; a negative discrimination index means the question may be misleading or inappropriate.

Step 6: Make Decisions Based on Analysis

Finally, use the data gathered from the difficulty and discrimination indices to make informed decisions.

• Review the questions with low difficulty indices and consider revising or replacing them.
• Pay attention to questions with negative discrimination indices, as these may need immediate attention.
• Use this analysis to improve future assessments and enhance student learning outcomes.

Conclusion

In this tutorial, we covered the essential steps for conducting an item analysis using the difficulty and discrimination indices of a Google Form test. By following these steps, you can gain valuable insights into your test's effectiveness.

Consider downloading the provided Excel file to assist with your calculations, and apply these principles to future assessments for continuous improvement in your evaluation methods.