The issue often is that management will not crush programmers if wrong. Managers aren't stupid. This isn't a competence issue primarily. This is a trust and ope

The issue often is that management will not crush programmers if wrong. Managers aren't stupid. This isn't a competence issue primarily. This is a trust and openness issue mainly. So the estimates were wrong? What do people believe about why they were wrong and how will people react? If that decends into defensive behavior ... Read the book.