The planning fallacy leads to which of the following descriptions?

• A. Underestimating how long tasks will take; overbooking; unexpected events
• B. Overestimating durations; underbooking
• C. Being biased by memorable events
• D. Applying base rates to test results

Answer: (A)

The planning fallacy is the tendency to underestimate the time, effort, and resources a task will require, leading to overcommitting and not accounting for potential delays or unexpected events. This happens because people focus on a best-case scenario and overlook practical obstacles, interruptions, or complexities that tend to arise in real work. That’s why the description involves underestimating how long tasks will take, filling the schedule with more work than can realistically fit, and being surprised by unforeseen issues.

The other descriptions describe different biases: thinking a task will take longer than it actually does is the opposite, while being biased by memorable events and applying base rates to test results refer to the availability heuristic and base-rate neglect, respectively.