The p-value for a test question shows how many students got that question right. It’s simply a number between 0 and 1 that tells you if a question was easy or hard for your class.
How to Calculate It
P-value = (Students who got it right) ÷ (Total students who took the test)
Real Classroom Examples:
- 20 out of 25 students answer correctly: P-value = 20/25 = 0.80 (easy question)
- 10 out of 25 students answer correctly: P-value = 10/25 = 0.40 (medium difficulty)
- 5 out of 25 students answer correctly: P-value = 5/25 = 0.20 (hard question)
What the Numbers Mean
When analyzing test questions, p-value often means the proportion of students who got the question right:
- P-value = 0.90: 90% of students got it right = EASY question
- P-value = 0.50: 50% of students got it right = MODERATE difficulty
- P-value = 0.10: 10% of students got it right = HARD question
The Relationship:
- Higher p-value = Lower difficulty (more students succeed)
- Lower p-value = Higher difficulty (fewer students succeed)
What This Means for Your Teaching:
- Questions with p-values 0.80-1.00: May be too easy, not helping you identify learning gaps
- Questions with p-values 0.40-0.70: Just right for discriminating between students
- Questions with p-values 0.00-0.30: May be too hard, poorly written, or covering material not taught
The Sweet Spot (0.3 to 0.7):
- These questions help you see which students really understand the material
- They’re not so easy that everyone gets them right
- They’re not so hard that everyone gets them wrong
- They give you the best information about student learning
What to Look For:
- Good balance: You want questions spread across different difficulty levels
- Most questions in the middle: The highlighted “optimum” range shows the best difficulty for learning
- Few extremely easy or hard questions: These don’t tell you much about what students know
How to Adjust Question Difficulty
When your p-values show questions are too easy or too hard, here’s how to fix them:
Standards and Alignment
- Too Easy (p > 0.8): Move to a higher level of the standard (from remembering facts to applying concepts)
- Too Hard (p < 0.3): Step back to foundational skills before testing advanced concepts
- Example: Instead of asking “What is 2+3?”, ask “Maria has 2 apples and buys 3 more. How many does she have now?”
Language and Vocabulary
- Too Hard: Replace complex words with simpler ones your students know
- Too Easy: Use grade-appropriate academic vocabulary
- Example: Change “Calculate the perimeter” to “Find the distance around the shape” for younger students
Structure and Context
- Too Hard: Break multi-step problems into smaller parts or provide more background information
- Too Easy: Add complexity by combining concepts or removing scaffolding
- Example: Instead of giving the formula, have students choose which formula to use
Answer Choices
- Too Easy: Make incorrect choices more appealing (common mistakes students might make)
- Too Hard: Remove obviously wrong answers that no one would choose
- Example: If testing 7×8, don’t include “2” as an option—use “54” or “58” instead
Visuals
- Too Hard: Add helpful diagrams, charts, or pictures to support understanding
- Too Easy: Remove visual aids that give away the answer
- Example: For geometry problems, include a labeled diagram for struggling concepts
Bias and Sensitivity
- Check for fairness: Ensure all students can relate to the context regardless of background
- Remove barriers: Avoid references that might confuse students from different cultures
- Example: Use “students in a class” instead of “players on a soccer team” if not all students play sports
Quick Rule: If you want your test to help identify which students understand the material, aim for questions with p-values around 0.50-0.70. Questions that everyone gets right or everyone gets wrong don’t give you useful information about student learning differences.
**Note This article intended to be viewed in conjunction with Question Analysis