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Cognition Corner – Well-Laid Plans

The human mind is riddled with quirks that can skew judgement and perception, regardless of where you stand on the corporate ladder. In fact, there’s a cognitive bias that can cause significant delays to projects and reduce the accuracy of your plans and workbacks. Working to eliminate this bias will improve the accuracy of your predictions and communications, and help you deliver on-time and on-budget.

Plan to be surprised
“The first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time.”
Tom Cargill, Bell Labs

When researchers asked people to estimate the time it would take them to complete a project under normal conditions, their answers were nearly identical to the estimates they gave for the completion time under ideal conditions. We simply don’t expect or effectively plan for hiccups and delays. This phenomenon is extremely well-studied, and is referred to as the Planning Fallacy.

The planning fallacy is rampant in human thinking. It affects us all, from university students to engineers to project managers. In one famous study, students were asked to assign dates to the probability of a major project being completed. They were asked what date it was 50% likely they were finished, 75% likely, and 99% likely. Here are the results:


Figure 1: When asked to specify a date that represents a 99% likelihood of project completion, less than half of students finish on time.

Similarly, taxpayers tend to mail in their forms a full week later than they predict. What’s interesting is that people are fully aware of the overoptimistic predictions they’ve made in the past. However, they truly believe that “this time will be different.”

As the project scales in complexity, its vulnerability to the planning fallacy increases as well. The Sydney Opera House took 10 extra years and nearly 12 times the initial budget to complete. It was a planning disaster of almost preposterous proportions.

So how do you prevent these massive oversights from occurring?

The first is to avoid “best case scenario” thinking for all but the simplest projects. If there are a lot of things that could go wrong, it is often likely that at least one of them will.

Second, have other people vet your plans. Interestingly, the planning fallacy rarely rears its head when assessing someone else’s capability. It seems that we are all hopeless idealists in regards to our own work, but we see other people more objectively. The solution is more transparency, cooperation, and communication. It usually is.

Remember to check this space regularly for future installments of Cognition Corner!

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