Optimism Bias in Transport Planning

In 2005, Professor Bent Flyvbjerg identified two main causes of misinformation in policy and management: strategic misrepresentation (lying) and optimism bias (appraisal optimism).

Strategic misrepresentation is the planned, systematic distortion or misstatement of fact—or lying—in response to incentives in the budget process.

Optimism bias or appraisal optimism is the demonstrated systematic tendency for people to be overly optimistic about the outcome of planned actions. This includes over-estimating the likelihood of positive events and under-estimating the likelihood of negative events.

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