Why are accurate estimates critical to effective project management?

Avoiding the Curse of the White Elephant

1. Why are accurate estimates critical to effective project management?
2. How does the culture of an organization influence the quality of
estimates?
3. What are the differences between bottom-up and top-down estimating approaches? Under what conditions would you prefer one over the other?
4. What are the major types of costs? Which costs are controllable by the project manager?
5. Why is it difficult to estimate mega project (e.g., airport, stadium)
costs and benefits?
6. Define a white elephant in project management. Provide a real-life example.