Things always take longer than expected. Always.

This post is also available in Dutch.

We tend to underestimate how much time a task should take. Why, though? Are there ways to get around our planning fallacies, to get things done on time?

The last time my supervisor had asked me when he could expect my completed project report, I had confidently said, “two weeks.” It’s been two months since, and I’m now about two weeks away from completing it… Or so I think.

The idea of us being terrible planners has now been around for nearly 50 years. There have been plenty of studies that have tried to understand why we fail to make realistic time plans, and where this planning fallacy might come from. Explanations ranging from “we want to be optimistic and hopeful about the future” (i.e. optimism bias, where we don’t consider the delays that occur outside our control), to “we just simply forget how much time it took us to do a similar task in the past” have all been suggested and tested.

The science of bad estimations
Roger Buehler and colleagues conducted a study in which they asked a bunch of students to estimate how much time they would need to complete writing their honour’s thesis. The students estimated 33.9 days. Then they were asked for an optimistic guess and a pessimistic guess, to which they answered 27.4 days and 48.6 days, respectively. However, the number of days that it took to complete their thesis was actually 55.5 days!

Nevertheless, these poor estimations were not only limited to perhaps “harder to predict” academic assignments. When the researchers asked students to predict how much time it would take them to complete simpler tasks like “fixing their bike”, “cleaning their apartment”, “writing a letter to a friend”, their predictions were also way off. While the average prediction was 5 days, the actual time it took to complete these simpler tasks was 9.2 days!

Please take note, it’s not just that we’re simply bad at predicting the time needed to complete our tasks, but particularly bad at taking our previous experiences into consideration when planning future tasks.

Not convinced yet?
The Sydney Opera House (that lotus-like structure you’ve seen in every picture of Sydney, Australia), was supposed to be completed in 1963. Construction had started in 1959. It was finally completed in 1973!

(This is when you take a walk and let this whole planning fallacy thing sink in.)

What now?
Well, there is a tiny bit of hope, and it lies in understanding that there are a couple of ways to get better estimates. It requires:

  1. constantly monitoring yourself,
  2. and asking a friend.

You should make some effort in recognizing and then considering a similar task you’ve completed before. After doing so, you can construct a better timeline for the task at hand. Then, while you monitor yourself and review your progress, you can adjust your timeline, which will make you more likely to meet those deadlines.

Now comes the friend bit. Research has shown that you tend to bypass the optimism bias when predicting others’ performance. So, before you jump to the task, go find a friend from within your field and ask them to give you an estimate. If you think they are being unreasonable and overly pessimistic, don’t say anything just yet. Start with whatever you need to do first, and then soon enough, you’ll more than likely find that they were right all along.

Now… where’s that report I should be writing.

Writen by: Suhas Vijayakumar
Suhas works as a PhD researcher at the Donders Institute during the day, where he tries to understand how differences in the formation and organisation of our brain makes us behave differently. And by night, he likes to think about education, science communication, fancy tech, and about being more productive.

Edited by Annelies and Marpessa.

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