Number Mistakes — Statistical & Probability Errors
Together Does Not Mean Caused
Correlation vs. Causation
In Plain English
Two things can rise together, fall together, or happen close together without one causing the other. They may share a third cause. They may be part of a larger pattern. Or the overlap may be partly luck. This bug is common because the mind loves clear stories with clear causes. But good reasoning with numbers asks harder questions: what else could explain the pattern, and what evidence shows real cause instead of simple connection?
Featured Example
Sales and sunshine
Ice cream sales rise when beach rescues rise. That does not mean ice cream causes the rescues. Hot weather drives both.
What this sounds like in Classrooms
- I listened to this song and got a good grade, so the song caused the result.
- Our class switched seats and test scores changed, so the seats must be the reason.
- Two events happened in the same week, so one gets blamed for the other.
What this sounds like in Business
- We changed the logo and revenue rose, so the logo caused the growth.
- More meetings happened during a strong quarter, so the meetings must have caused success.
- A new dashboard launched near a recovery, so the dashboard gets all the credit.
What this sounds like in Real Life
- I wore my lucky shoes and we won, so the shoes caused the win.
- My headache started after the snack, so the snack must be the reason.
- Social media use rose, so every teen problem gets blamed on it.
Examples from Literature or Fiction
Sherlock Holmes stories
Wrong investigators connect two nearby facts and call it solved too early.
A visible connection gets mistaken for true cause.
Oedipus Rex
People search hard for a clean cause that explains suffering and disorder.
The hunger for cause can outrun the evidence.
Folk tales and omens
Signs and events are often linked as cause because they occur together.
Shared timing becomes false proof of control or explanation.
Why People Fall for It
A clear cause feels satisfying. It turns confusion into story. The problem is that the story may be wrong.
How to Spot It
- Two things happen together and the conclusion jumps straight to cause.
- Other possible causes are ignored.
- Timing is treated like proof.
- The explanation sounds neat but thin.
What to say instead
- What else could explain both events?
- Do we have evidence of real cause, not just overlap?
- Could a third factor be driving both?
- Together is not the same as because.
Common Confusion
People mix this up with:
Compare Nearby Ideas
Quick Comparison
Base Rate Neglect vs Availability Heuristic
Base Rate Neglect ignores the big background numbers, while Availability Heuristic overweights whatever example comes to mind most easily.
Mini Practice
Question: A company changes its homepage and then sales rise during the holiday season. The team says the homepage change caused the rise. What is the bug?
Answer: Correlation vs. Causation.
The timing overlaps, but other causes like seasonality could explain the change.
Remember This
When two things move together, ask what else might be moving them.
Related Brain Bugs
Base Rate Neglect
Ignoring The Big Background Numbers
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After the final play, fans say the winning move was obvious, even though most people were arguing about it before it happened.
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