# Item Analysis: Group Data

**Approach 2: Analyzing patterns in choices of incorrect responses — group data. **Table 1, focus on Columns 8–11.

Columns 8–11 go deeper into the data, showing the percentage of students who selected each option of the multiple-choice item. The question that this part of table answers is:

*Which wrong answer was selected most often?*

**Table 1: Item Analysis:
Multiple-Choice Percentage Correct & Percentage Choosing Each Option**

Looking at #1a; the correct answer was C, so we look at the data for distractors A, B, and D. The distractor that was selected most often was D. What does this mean?

When distractors (wrong answers) are written for the typical misunderstanding and errors that students make, diagnosing learning needs is easier. Below is item 1a, the multiple-choice part of item 1 on the test. The distractors were written to diagnose common student errors. In parentheses are the misunderstandings that would lead to choosing each distractor.

**1.a. A rectangle is 6 feet long and has a perimeter of 20 feet. What is the width of this rectangle? **

- 3.33 feet (confusing perimeter with area)
- 8 feet (didn’t divide width by 2)
**4 feet (correct answer)**- 14 feet (didn’t multiply length by 2 or divide width by 2)

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