What do I need to know about the planning fallacy?

The Irrational Tech: Part 1

Julia Clavien
5 min readNov 5, 2016


This is a series. Find Part 0 here.


Everyone was in the room — the devs, QA, analysts, PMs and more. I looked over the plans and confidently suggested that given our velocity we would hit our date. There were murmurs of agreement around the room. I felt confident, we had a great team, and there was contingency.

Yes, on other projects in the past things had taken longer than expected, but this one was “different”…

Well I’m sure you can see where this going.

The client was not impressed when delivery took twice as long as planned.

The Planning Fallacy

The Planning Fallacy relates to our tendency to systematically underestimate the time & resources…



Julia Clavien

Curious to a fault. Technology | Psychology | Philosophy. All opinion subject to change. ☺ linktr.ee/juliaclavien