I suspect that anyone who has been involved in any form of project has seen this at work. You look at the project, build a plan, come to a view of how long it’s going to take. You’ve done this type of activity before and should know how long it takes. Within days, though, it’s clear that the plan is not going to work and that time is not on your side, any contingency in the plan looks like a necessity and help from a time-lord would be welcome. You’ve just been caught in the Planning Fallacy.
The same also applies for cost estimates and our ability to estimate the benefits of a project. The project management triangle tells us that we can choose two between cost, scope and schedule; but the reality is that we often get all three wrong.
Individuals and organisations get caught out in the most spectacular fashion, but it would be too easy to attribute ever project overrun to this one bias – remember there are over 160 biases to choose from.
I’ve been caught in this one so many times that I now have a rule: whatever I plan the duration to be I double it; even then I still get caught out.
Do you have an approach for overcoming this bias?
Here’s Daniel Kahneman who was one of the people who came up with the idea: