A p-value is a number that helps you determine whether the results you’re seeing are likely due to chance or if they represent a real difference or effect.
Think of it this way: Imagine you try a new teaching method with half your class and keep the old method with the other half. At the end, the “new method” group scores higher on a test. The p-value helps answer: “Could this difference just be random luck, or did the new method actually work?”
Key Points:
What the number means:
- P-values range from 0 to 1 (often written as decimals like 0.05 or percentages like 5%)
- Lower p-values = more confident the results are real
- Higher p-values = results might just be chance
The magic number: Most researchers use 0.05 (or 5%) as their cutoff
- If p-value is less than 0.05: “This difference is probably real!”
- If p-value is greater than 0.05: “This might just be random chance”
Classroom example: You notice boys seem to participate more than girls in your class discussions. You collect data for a month. If the p-value is 0.02, you can be fairly confident there’s a real difference. If it’s 0.30, the difference might just be coincidence.
Remember: A p-value doesn’t tell you HOW important or HOW big a difference is—just whether it’s likely to be real rather than random.