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(PS-1971) The Planning Fallacy and its Effect on Realistic Project Schedules

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Primary Author: Mr Jeffrey Valdahl
Co-Author(s): Ms Shannon A Katt

Audience Focus: Intermediate
Application Type: Research
Venue: 2015 AACE International Annual Meeting, Las Vegas, NV, USA

Abstract: “How long do you think that task will take?” It’s a question that is asked frequently during the course of a project, but is often answered with little or no factual basis. Project team members typically underestimate the time needed to complete a task they are responsible for. This tendency has been referred to as the “Planning Fallacy,” and it can have a dramatic effect on developing a realistic overall project schedule. This paper examines various causes of the Planning Fallacy, including optimism bias, lack of task unpacking, and short memory.

As a project manager or planner, it’s important to recognize when these psychological effects are impacting your project schedule. This paper uses examples from various projects to show where this challenging planning issue is likely to occur. Identifying where adjustments need to be made at both the task and overall project level is essential in developing a project schedule that is both achievable and reasonable.