IndexOther reasons includeWe forgot how long it took last time.How the Planning Fallacy Affects You TodayHow to Stop the Planning FallacyUse Software to Help Predict the workThe role of software in eliminating the planning fallacyThe planning fallacy in action The planning fallacy is a phenomenon that no matter how much time you think you need to do a task, you actually need more time . Regardless of how many times you've done the task before or how in-depth your specialized knowledge is, there's a high probability that you won't give yourself enough time to do the job. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Sound familiar? I'm sure you've worked with project team members who are optimistic in their estimates and project schedules with milestones that seemed achievable, but are now due next week. And, well, suddenly the workload looks very different. The planning fallacy was first proposed by two psychologists, Daniel Kahneman and Amos Tversky in 1979. Interestingly, the planning fallacy phenomenon occurs only in the evaluation of one's own workload, not that of someone else. As it turns out, we're much better at being realistic and even pessimistic about our colleagues' ability to deliver. There are many reasons why we get estimates wrong. Kahneman and Tversky's original proposal was that when we plan our work we focus on the most optimistic scenario, even if we have experiences that contradict it. It's a bias of optimism. Other reasons include wishful thinking. We want to be able to finish the job quickly and easily; so we plan based on hope rather than facts. We forgot how long it took last time. We are focused on a positive outcome for the project, so we don't think in terms of what could go wrong and we anticipate the facts that unexpected surprises could slow down the work. Even if we have done something similar in the past that could be used as a baseline quote, we discard it because this is a “new” project and so that experience somehow doesn't count. When we look at similar tasks, we remember all the things we did well and blame the delays on other people and outside influences. Therefore, past experience is not representative and is not used to estimate the current period. All of these reasons are likely to occur on a subconscious level rather than intentional or voluntary. One explanation for this is that people deliberately focus on the most optimistic outcome, as this creates a better business case, and the better the business case, the more likely it is that the project will be approved. A little overshoot later isn't that difficult to deal with if you have a vested interest in getting the project approved in the first place. How the Planning Fallacy Affects You Today The planning fallacy is affecting your project, I guarantee it. You may not have noticed it yet, especially if your team is working hard to deliver on time. But unless you've done something specifically to counteract it, optimism bias is alive and well in your project planning. The impact here is that tasks take longer than expected. This results in delays, overworked staff, low confidence in project delivery and dissatisfied stakeholders. In really severe cases, your project can fall so far behind.