be overly optimistic. Ex post evaluations indicate a bias where investment costs are higher and benefits lower on average … than predicted ex ante. These authors argue that the bias must be attributed to intentional misrepresentation by project … developers. This paper shows that the bias may arise simply as a selection bias, without there being any bias at all in …

situation is uncertain and complex, and when bias is likely. Non-experts who know the Golden Rule can identify dubious forecasts … quickly and inexpensively. To date, ignorance of research findings, bias, sophisticated statistical procedures, and the …