Why is the range so much higher for IT projects than construction projects?

The Delphi Method
1. What kinds of estimates are best suited for this method?
5.3 Estimate Accuracy
1. Why is the range so much higher for IT projects than
construction projects?
5.5 Avoiding the Curse of the White Elephant
1. Can you identify personal examples of white elephants?
2. What else do you think Olympic organizers could do to make
the event more sustainable?