Base Rate Neglect
Ignoring The Big Background Numbers
Number Mistakes
A test flags a rare condition, and someone assumes the condition is now very likely without looking at how rare it is in the first place.
Learn this bugStatistical & Probability Errors
Number Mistakes
Number mistakes happen when people skip base rates, trust tiny samples, or confuse patterns with proof.
Why this Category Matters
Better reasoning with numbers keeps you from overreacting to luck, streaks, and flashy charts.
Inside this Topic
7 lesson pages and 1 comparison links currently live in this section.
How it Differs
These errors focus on evidence and probability.
Heuristics often feed them when people guess too fast.
Featured Examples
Correlation vs. Causation
Together Does Not Mean Caused
Number Mistakes
Ice cream sales rise when beach rescues rise. That does not mean ice cream causes the rescues. Hot weather drives both.
Learn this bugLaw of Small Numbers
A Tiny Sample Gets Treated Like The Whole Truth
Number Mistakes
A teacher looks at three quiz results from a new method and decides the method clearly works for the whole grade.
Learn this bugRegression to the Mean
Extreme Results Often Drift Back Toward Normal
Number Mistakes
A player has the best game of the season, then plays more normally next time, and people act like one speech or superstition caused the c...
Learn this bugTexas Sharpshooter Fallacy
Pick The Pattern After The Fact
Number Mistakes
A team looks at many product metrics, finds the two that moved together, and presents that pair as if the trend had been clear from the s...
Learn this bugGambler's Fallacy
A Short Streak Feels Like It Must Reverse
Number Mistakes
After five heads in a row, someone says tails is now much more likely on the next flip because the streak has to end.
Learn this bugBrowse this topic
Gambler's Fallacy
A Short Streak Feels Like It Must Reverse
Number Mistakes
After five heads in a row, someone says tails is now much more likely on the next flip because the streak has to end.
Learn this bugLaw of Small Numbers
A Tiny Sample Gets Treated Like The Whole Truth
Number Mistakes
A teacher looks at three quiz results from a new method and decides the method clearly works for the whole grade.
Learn this bugRegression to the Mean
Extreme Results Often Drift Back Toward Normal
Number Mistakes
A player has the best game of the season, then plays more normally next time, and people act like one speech or superstition caused the c...
Learn this bugBase Rate Neglect
Ignoring The Big Background Numbers
Number Mistakes
A test flags a rare condition, and someone assumes the condition is now very likely without looking at how rare it is in the first place.
Learn this bugTexas Sharpshooter Fallacy
Pick The Pattern After The Fact
Number Mistakes
A team looks at many product metrics, finds the two that moved together, and presents that pair as if the trend had been clear from the s...
Learn this bugSimpson's Paradox
The Big Total Tells A Different Story Than The Smaller Groups
Number Mistakes
One teaching method looks worse across the whole school, but inside both beginner and advanced classes it actually performs better.
Learn this bugCorrelation vs. Causation
Together Does Not Mean Caused
Number Mistakes
Ice cream sales rise when beach rescues rise. That does not mean ice cream causes the rescues. Hot weather drives both.
Learn this bugCommon Warning Signs
A tiny sample is treated like a law.
Two things happen together and are called cause and effect.
Beginner-Friendly Starting Points
Together Does Not Mean Caused — Correlation vs. Causation
Ignoring The Big Background Numbers — Base Rate Neglect
A Tiny Sample Gets Treated Like The Whole Truth — Law of Small Numbers
A Short Streak Feels Like It Must Reverse — Gambler's Fallacy
Quick Examples
Three coin flips
A short streak gets treated like a reliable pattern.
Practice this Topic
Use a short quiz or drill to check whether you can tell this category apart from nearby thinking traps.