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time
You consistently underestimate the time tasks will take.
A 1994 study found that students predicted they would finish their thesis projects in 33 days, but actually took an average of 55 days.
This bias persists because you imagine an ideal scenario where nothing goes wrong, ignoring your own historical track record with similar tasks. Your brain creates a best-case narrative that overrides reality.
Your future plans are usually optimistic fantasies rather than accurate predictions.
Where this comes from
- Study
- Buehler, Griffin, and Ross, 1994
- What the check found
- The study by Buehler, Griffin, and Ross (1994) is the classic source for the planning fallacy. The cited numbers are accurate to the study's results (33.9 vs 55.5 days).
- Confidence
- Well replicated
Related
One of these every day, and every one names the study it came from. When a finding is contested, it says so.