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Statistics test
Statistics is full of ideas that are easy to state and easy to get backwards: what a p-value means, when an average misleads, why a poll of a thousand people works for a whole country.
Towns that sell more ice cream have more drownings. What’s the most likely explanation?
About this test
Every wrong answer here is a named mistake. You’ll see why after each question, and at the end you get a course that starts from the ones that caught you.
Questions people ask
What does a p-value actually mean?
How surprising your data would be if there were no real effect. A small p-value means the data would be unusual under that assumption. It isn’t the chance the result is wrong.
Is this good practice for a stats exam?
It covers ideas that come up on most intro statistics courses and exams, like AP Statistics and first-year university stats, but it tests understanding rather than calculation.
Why doesn’t a bigger country need a bigger poll?
A random sample’s precision depends on its size, not the size of the population it’s drawn from, the same way a spoonful of well-stirred soup tells you its saltiness whatever the size of the pot.
Read more
- Correlation vs Causation: How to Tell the Difference, With Examples
- What a p-Value Actually Means (and the Three Ways People Misread It)
- Simpson's Paradox: Better in Every Group, Worse Overall
- Regression to the Mean: Why Extreme Results Don't Last
- Mean vs Median: Which Average Should You Trust?
- Survivorship Bias: The Planes That Didn't Come Back