Why is it difficult for project managers to make good estimates?

Friday, July 12th, 2013 By Jack Nevison

To paraphrase an old Army saying: "Proper prior planning prevents pitifully poor performance." Known as the "seven P's," this adage also applies to civilian life, particularly to projects.

Good project managers know that projects will fail if they are not planned properly, especially if they involve unfamiliar work. But the best managers know that even projects dealing with familiar work can be the victims of poor planning.


Because humans have certain mental biases that can affect our judgment and, by extension, our work. These biases are not easy to avoid, but it's crucial for project managers to do so.

For example, according to a blog post on The Project Management Hut, "project managers have a natural tendency to underestimate, and their guesses are vetted through a process designed to save money, rather than arrive at an accurate estimate."

In the white paper "Good Estimates and Bad Biases," New Leaf Project Management explores the research on why it is so difficult to make accurate estimates when planning a project.

Readers will learn why managers estimate too high or too low, and why they rely too much on evidence that confirms their own biases while ignoring contradictory evidence. Readers will then learn how to avoid making overconfident estimates.

Project managers seeking to obtain or maintain their PMP® certification can read this white paper, or one of 15 others produced by New Leaf, then assess their knowledge by completing a short post-test. Earn affordable PDUs for completing these quizzes, as well as bonus points for answering quickly!

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