Optimism Bias
- “why do I think it won't happen to me”
- “optimism bias explained”
- “why projects always run over”
- “unrealistic optimism research”
:: COMPARE ::
Optimism biasvsOptimism
The short answer
Optimism is a disposition — expecting things to go well. Optimism bias is an arithmetic error — rating your own odds better than comparable people's when they can't be. Cheerfulness isn't the bias; the impossible maths is.
Side by side
| Aspect | Optimism bias | Optimism |
|---|---|---|
| Is | A judgment error | A temperament |
| Measurable as | Impossible group maths | Self-report |
| About | Comparative risk | General outlook |
| Universal | Not quite (79%) | No |
Which one you meant
Readers who land here meaning Optimism Bias rather than Optimism are usually searching for phrases like “why do I think it won't happen to me”, “optimism bias explained”, “why projects always run over”.
Where the confusion comes from
“Optimism bias is just being an optimistic person.”
It's a measurable error in probability judgment, not a temperament. The signature is structural: a whole group cannot all be at below-average risk of divorce, yet Weinstein's 258 students collectively claimed exactly that.
Read either one in full