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Constantly late with work? Blame the planning fallacy

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“I love deadlines. I love the whooshing noise they make as they go by,” the late British author Douglas Adams once famously quipped.

Most of us can empathise with this feeling of time rushing before our eyes as we struggle to complete a task. At least most of our delays are not the cause of national humiliation, but missed deadlines have led to red faces in politics on numerous occasions. Consider the Sydney Opera House. The Australian government first commissioned the project in 1958, with an expected completion date of 1963. Yet it didn’t open until 1973 – 10 years late – at enormous extra cost.

Today’s prominent examples include the Hong Kong-Zhuhai-Macao Bridge, Berlin’s Willy Brandt Airport, and Britain’s much-vaunted HS2 high-speed railway, which is now seven years behind target.

A cognitive quirk called the planning fallacy leads us to consistently underestimate how long it will take us to complete a project
Why are we so bad at sticking to schedules? The explanation can’t just be laziness or procrastination, since in many of these cases the employees were working at full productivity. Instead, psychologists tend to blame a cognitive quirk called the planning fallacy, which leads us to consistently underestimate how long it will take us to complete a project. The result is that our original deadlines are flawed from the get-go.

Whether you are managing a complex professional project, or simply trying to renovate your house, an understanding of the planning fallacy will help to ensure that you meet every goal on time.

Sydney Opera House
Due to planning fallacies, the Sydney Opera House – initially budgeted at around $5 million – ended up costing nearly $70 million and was completed ten years late (Credit: Alamy)

The concept of the planning fallacy was first introduced by the Nobel Prize-winning psychologist and economist Daniel Kahneman and his collaborator Amos Tversky in the 1970s, who were inspired by the habits of their colleagues. They were surprised to note that their colleagues routinely underestimated how long a project would take to complete even after they had missed many deadlines on similar projects in the past. They weren’t learning from their errors.

Surveys confirm that the planning fallacy is astonishingly common. In schools and universities, it can be seen among both staff and students. In IT, surveys suggest that fewer than one third of projects meet their initial deadline. In industrial research and design, projects take about 3.5 times as long as expected. And as Adams had noted, it is the bane of authors: informal estimates suggest that up to 90% of professional writers are late delivering their manuscripts. The planning fallacy could also help us understand why people fail to file their tax returns on time, year after year and leave Christmas shopping until it is almost too late. In each case, previous failures did not appear to improve their chances of meeting a deadline in the future.

In IT, surveys suggest that fewer than one third of projects meet their initial deadline
One theory is that the planning fallacy arises from our broader tendency to focus on fine details of a scenario, rather than the big picture – what Kahneman calls “taking the inside view”. As a freelance writer setting out the schedule for an assignment, for instance, I might start to tot up all the people I need to call, the papers I need to read and the places I need to visit. Since those particular factors will be different from assignment to assignment, I may not see my previous experiences as being relevant for this particular project.

The problem is that our failures to meet deadlines often come from less predictable, more general factors – such as new distractions from other tasks, difficulties with travel or gaining the necessary supplies, or illness – that could all contribute to a delay. It’s these kinds of difficulties that probably caused us to miss deadlines in the past – and recognising that fact could help us to pre-empt some of those issues in the future. By focusing too much on the highly specific details of our current task and ignoring our past experiences, however, we fail to take those possibilities into account.

Suppliers unloading
When we confidently tell ourselves that suppliers are going to be more reliable this time around, that’s motivated reasoning doing the talking (Credit: Alamy)

This tendency may be exacerbated by “motivated reasoning” – we often look only for the evidence that suits our goals, and it is often within our interests to feel that a project can be completed quickly and with less effort, leading us to ignore or dismiss clues that it might take longer. We could tell ourselves that all our suppliers will be more reliable this time, or the transport problems that set us back last time were a one off, because we want to feel confident that the project will go more smoothly this time.

Motivated reasoning could be a particular problem in businesses where people could be rewarded for unrealistically short deadlines, which might explain why it is particularly rife in IT. “It could be something to do with the need to be competitive to secure contracts and thus underestimating the costs involved when tendering,” says Kevin Thomas at the University of Bournemouth in the UK. Note that this does not necessarily involve deliberate deception: thanks to motivated reasoning, people could easily be fooling themselves rather than consciously pulling the wool over their clients’ eyes.

We often look only for the evidence that suits our goals, leading us to ignore or dismiss clues that it might take longer
An understanding of the planning fallacy can explain why even our best attempts at time management can sometimes backfire. In a 2003 study, a group of Canadian undergraduates were asked to make detailed plans to execute tasks such as their Christmas shopping. Against expectation, their time estimates were even more unrealistic than people who had not put together a schedule. The problem was that they were still focusing on the more specific tasks to complete, rather than all those less-predictable distractions and challenges that might prevent them from carrying out those duties on time. Their detailed plans had simply given them a false sense of security.

Clearly, these were fairly simple tasks, and if you are embarking on a complex project, it will still be essential to unpack the necessary steps. Research by Katherine Milkman at the University of Pennsylvania and Leslie John at Harvard Business School, for example, shows that setting “implementation intentions” can reduce procrastination and increase the chance that people will follow through with their plans.

winter village NYC
Haven’t started Christmas shopping yet? Be sure to lay out the specific tasks and potential challenges before hitting the markets (Credit: Alamy)

But if you want to make more realistic plans in the first place, you should also pay greater attention to previous experiences and resist the temptation to dismiss their relevance for the problem at hand. (If you have not experienced this kind of project yourself, look to the average of people in a similar position.)

The circumstances may not be identical – it’s unlikely that you will face exactly the same challenges this time round – but as a rough baseline, these previous experiences help you to set a better baseline estimate of the time to complete a project, which you can then refine with the particular details. Thomas says that he applies this strategy himself. “I try not to treat the current task as something that’s unique from what I’ve encountered before,” he says.

It sounds unnervingly simple, but the research shows that it really works. If you take the same advice, that unsettling “whooshing sound” of broken promises flying by can be a thing of the past, as you deliver each project with the deadline still firmly in sight.

David Robson is the author of The Intelligence Trap: Why Smart People Do Stupid Things and How to Make Wiser Decisions. He is d_a_robson on Twitter.