People systematically underestimate how long tasks will take to complete.
Kahneman and Tversky's 1979 term. The Sydney Opera House was estimated at seven million dollars and four years; it cost 102 million and took fourteen. Reference class forecasting is the remedy.
In practice
- A team late on its last six projects estimates the seventh from how long the work should take, rather than from how long the last six took.
- A householder who allows a weekend for painting a room is not being foolish about paint; they are omitting the moving, masking and drying that the estimate never contained.
- Further reading
- Wikipedia
- Subject
- Decision-making & Reasoning
- Essay
- The catalogue of predictable errors