People Are Consistently Overly Optimistic When Asked To Predict Their Own Future Behavior

No surprise here. When I was having to make estimates for how long it would take to finish writing, testing, and documenting a program for a government contract, I multiplied my first estimate by 3, because I had learned from experience that it usually took me about three times as long as I thought it would. So I usuall met my estimates. But it seemed that most people could learn from their own experience, but would always underestimate. This study gives a technique that might be able to get more accurate estimates.

http://www.sciencedaily.com/releases/2009/02/090226110705.htm

ScienceDaily (Feb. 26, 2009) — The next time a contractor tells you the kitchen remodeling will be done in six weeks, you might ask him to get real and reconsider his estimate.

People often fail to remember that the world is not ideal when they predict when they will complete a project, how frequently they will exercise, or how much money they will save. However, a subtle reminder of the difference between ideal and realistic predictions can yield a more accurate estimate, according to new research from Duke University's Fuqua School of Business and the Wisconsin School of Business.

In a series of experiments, Duke Marketing Professor Kurt Carlson and Professor Robin J. Tanner of Wisconsin found that people were consistently overly optimistic when asked to predict their own future behavior.
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Carlson and Tanner found that unrealistic expectations could be overcome by asking people to make two sets of predictions: when they would complete a task "in an ideal world," followed by a straightforward prediction of when they might actually complete the task. Participants who answered both questions reported inflated intentions in the ideal-world scenario, but significantly more realistic predictions in response to the second question.
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"By asking people how they would perform in an ideal world, and following up by asking how they would perform without reference to the ideal world, we get people to think about the factors that can impede their performance," Tanner said. "It's a way of helping people heed the many factors that can keep them from behaving as they would like to."

"We've known for a long time that people underestimate how long it will take to complete a project -- look at the Big Dig in Boston. What we have not known is how to fix the problem," Carlson said. "Now we do."