Question Difficulty (Rasch)

What Item Difficulty Means

Think of Rasch analysis like a “quality meter” for your test questions. Just like a thermometer tells you if it’s too hot, too cold, or just right outside, Rasch analysis tells you if your questions are too easy, too hard, or just right for your students.

Reading Your Question Quality Chart

The Scale (-4 to +4)

This horizontal line works like a ruler for difficulty:

• Left side (negative numbers) = Easier questions
• Center (around 0) = Just-right questions
• Right side (positive numbers) = Harder questions

The Blue Box

The colored box shows where your specific question lands on this difficulty scale. The number inside (like -0.47) is your question’s “difficulty score.”

What Different Charts Mean

Excellent Questions (Within Optimum Range)

What you’ll see: Blue box near the center, labeled “Within Optimum Range”

• Difficulty score between -0.5 and +0.5
• What this means: This question perfectly matches your students’ ability level
• Why it’s good: Students who know the material will get it right, students who don’t will get it wrong
• Keep doing: Use questions like this – they help you accurately assess learning

Too-Easy Questions

What you’ll see: Box positioned far to the left, possibly labeled “Below Optimum Range”

• Difficulty score like -2.1 or lower
• What this means: Almost all students got this right, even those who don’t understand the concept
• The problem: You can’t tell who really learned the material
• Action needed: Make the question more challenging or remove it

Too-Hard Questions

What you’ll see: Box positioned far to the right, possibly labeled “Above Optimum Range”

• Difficulty score like +2.3 or higher
• What this means: Even students who understand the material struggled with this question
• The problem: The question might be unfairly difficult or confusing
• Action needed: Simplify the question or check if you need to teach this concept more

Slightly Off Questions

What you’ll see: Box somewhat left or right of center, might be labeled “Near Optimum Range”

• Difficulty scores like -0.8 or +0.9
• What this means: Close to ideal, but could be improved
• Action needed: Minor adjustments to make them just right

The Goal: “Just Right” Questions

You want most of your assessment questions to fall in the “just right” zone – challenging enough to measure student learning but not so difficult that they become frustrating or unfair.

How to Review and Adjust Item Difficulty

1. Standards and Alignment

To Make Questions Easier:

• Focus on the most basic part of the standard first
• Test one concept at a time instead of combining multiple skills
• Ask about facts before asking students to analyze or evaluate

To Make Questions Harder:

• Combine two related concepts from the standard
• Ask students to apply what they learned to a new situation
• Move from “remember” to “understand” to “apply” levels

Example: Instead of “What is photosynthesis?” (too easy), try “How would a plant’s photosynthesis change if it received less sunlight?” (just right)

2. Bias and Sensitivity

To Make Questions Fairer and More Accessible:

• Use situations all students can relate to (home, school, community)
• Avoid references to expensive activities or items
• Include diverse names and backgrounds in word problems
• Remove unnecessary cultural knowledge requirements

Example: Change “During your family’s ski vacation…” to “When you’re outside in winter…” – not all families take ski vacations, but all students experience winter.

3. Language and Vocabulary

To Make Questions Easier:

• Use shorter sentences
• Replace difficult words with simpler ones (use “buy” instead of “purchase”)
• Define technical terms you must use
• Remove unnecessary words

To Make Questions Appropriately Challenging:

• Include grade-level vocabulary students should know
• Use complete, well-structured sentences
• Include academic language from your subject area

Example:

• Too hard: “Calculate the perimeter utilizing the given measurements”
• Just right: “Find the perimeter using these measurements”
• Too easy: “Add up all the sides”

4. Structure and Context

To Make Questions Clearer:

• Give students all the information they need
• Use familiar formats (like the way you teach in class)
• Put the most important information first
• Make sure the question is clearly stated

To Add Appropriate Challenge:

• Provide real-world scenarios that require thinking
• Give students information they need to sort through
• Create multi-step problems

Example: Instead of just asking for a math calculation, set it in a context like planning a school event or calculating materials needed for a project.

5. Answer Choices

To Make Questions Easier:

• Make wrong answers obviously incorrect to students who know the material
• Avoid tricky wording
• Make all choices about the same length
• Include only one clearly right answer

To Make Questions More Challenging:

• Create wrong answers based on common mistakes students make
• Use “best answer” format where students must choose the most complete response
• Make sure all choices could seem reasonable at first glance

Example:

• Too easy: A) 2+2=5 B) 2+2=4 C) 2+2=7
• Just right: A) 2+2=3 B) 2+2=4 C) 2+2=6 (wrong answers reflect common calculation errors)

6. Visuals

To Support Student Success:

• Include clear diagrams that help explain the question
• Use charts or graphs that make information easier to understand
• Make sure images are large enough to see clearly
• Only include visuals that help with the question

To Add Appropriate Challenge:

• Ask students to read information from graphs or charts
• Include diagrams that students must interpret
• Use visuals that require students to make connections

Example: Instead of just asking “What is 25% of 100?”, show a pie chart and ask students to identify which section represents 25%.

Practical Steps for Question Improvement

When Your Question is Too Easy:

1. Look at your standard – Are you testing the full depth of what students should know?
2. Check your vocabulary – Could you use more grade-appropriate academic language?
3. Examine answer choices – Are the wrong answers too obviously wrong?
4. Add context – Can you put this in a real-world situation that requires more thinking?

When Your Question is Too Hard:

1. Simplify language – Are there unnecessary complex words or sentences?
2. Check for bias – Does this require knowledge not all students have?
3. Review visuals – Are images confusing rather than helpful?
4. Break it down – Can you test this concept in smaller, clearer parts?

When Your Question is Close but Not Quite Right:

1. Fine-tune vocabulary – Small word changes can make big differences
2. Adjust answer choices – Make them slightly more or less challenging
3. Modify context – Add or remove one element to shift difficulty

The Big Picture

Think of this like Goldilocks and the Three Bears, but for test questions:

• Too easy = Students don’t have to think or demonstrate real understanding
• Too hard = Students give up or get frustrated, even when they know the material
• Just right = Students who learned the concept succeed, those who didn’t struggle appropriately

The goal isn’t to make every question the same difficulty, but to ensure each question serves its purpose in measuring what your students have learned. When most of your questions fall in that “just right” zone, you can trust that your assessment accurately reflects student understanding.

Remember: Good assessment questions aren’t about tricking students – they’re about giving students who understand the material a fair chance to show what they know, while still being challenging enough to distinguish between different levels of understanding.

Practical Strategies for Implementation

When Questions Are Too Easy:

1. Add a layer of application or analysis
2. Introduce more sophisticated vocabulary
3. Create more nuanced answer choices
4. Require multi-step reasoning

When Questions Are Too Hard:

1. Break complex concepts into smaller parts
2. Provide more context or background information
3. Simplify language while maintaining content rigor
4. Offer clearer distinctions between answer choices

Regular Review Process:

1. Analyze which questions consistently challenge students appropriately
2. Identify patterns in questions that are too easy or too hard
3. Gather student feedback on question clarity
4. Collaborate with colleagues to review item quality

The Bottom Line

Creating well-calibrated assessment items is an ongoing process. By systematically reviewing and adjusting these six key areas, you can develop questions that accurately measure student learning while being fair and accessible to all students. Remember, the goal isn’t to make tests easier or harder overall, but to ensure each question provides meaningful information about what your students know and can do.

**Note This article intended to be viewed in conjunction with Question Analysis