Why We’re So Bad at Predicting How Long a Task Should Take

The famous Sydney Opera House was originally estimated to be completed in 1963, but it wasn’t completed until 1973. That’s ten long years later than was originally planned. This is an exaggerated example of a tendency that we all have: we underestimate how long it will take us to complete a task or project. This variation of poor time management is called The Planning Fallacy. (Incidentally, the original cost for the Sydney Opera House was $7 million; it ended up costing $102 million.)

The Planning Fallacy is a cognitive bias–or a distortion in the human mind–which refers to people’s tendency to underestimate how long they will need to complete a task. As social psychologist Heidi Grant Halvorson, Ph.D., states:

“[H]uman beings are generally pretty lousy when it comes to estimating the time they will need to complete a task.”(Source.)

And this is why we create To Do lists that are a mile long, fully expect to get everything on the list done, and feel defeated when we invariably fail to do so.

The Planning Fallacy applies to everything:

• Writing a paper, or studying for a test, if you’re a student.
• Going grocery shopping and preparing a three-course meal, if you’re a homemaker.
• Preparing a presentation for your boss, if you hold a corporate job.
• Getting ready for an evening out, if you’re going out on a date.

This article will explain The Planning Fallacy in greater detail, and it will give you tips and tools to overcome it (or at least improve your ability to predict how long different tasks should take).

Three Reasons for The Planning Fallacy

The Planning Fallacy can be attributed to three basic biases we have when estimating how long it will take to do just about anything:

• We fail to consider past experiences.
• We consider the best possible outcome.
• We focus on the overall task, not on subcomponents.

Each of these is explained below.

We Fail to Consider Past Experiences

First, we fail to consider our past experiences when planning. When planning, people perceive the specific task or activity that they need to complete as unique. That is, they tend to disregard the time that was needed to complete the same, or similar tasks or activities, in the past.

Suppose that it’s Saturday morning and you’re talking to a friend on the phone. You decide to invite them over for coffee that afternoon, and they accept. There are several things that you want to get done before they arrive, including straightening up the living room.

Even though it usually takes you about an hour to vacuum the living room, dust the table surfaces, and so on, when planning the afternoon with your friend you’re very likely to tell yourself something like the following:

“I can get the living room straightened up in about fifteen minutes.”

Therefore, you leave the task of putting the living room in order until there’s less than half an hour left before your friend arrives. When they do arrive, you’re only halfway through the task, and you have to go through the embarrasment of apologizing for the mess.

If you hold a job, think of how many times you’ve taken tons of work home over the weekend, fully intending to get it all done, and then you didn’t have enough time to complete even half of the work. And then what happens?

• Instead of learning from this experience and taking home less work the next weekend, you do the same thing all over again.
• The week after that you do the same thing once more.
• Weekend after weekend you lug home tons of work which you should know from past experience that you’re not going to be able to get through.

We Consider the Best Possible Outcome

Second, our future plans tend to be “best-case scenarios.” We ignore all of the things that could go wrong. That is, we underestimate the likelihood of unexpected, but plausible, complications and obstacles.

In the example of your friend coming over on Saturday afternoon, what if the vacuum cleaner breaks down and you have to run out to the store and get a new one? What if you drop a vase while dusting and you have to pick up all of those tiny pieces of broken glass? When you plan cleaning the living room before your friend arrives, it’s very likely that you’ll have a vision of yourself gliding through the task effortlessly, with everything magically falling into place.

We Focus on the Overall Task, Not On Subcomponents

Third, and last, we don’t think about all the steps or subcomponents that make up the task. Instead, we tend to look at the overall task. “Straighten up the living room” sounds simple enough, but once you take into account each individual task that goes into straightening up the living room, it’s a different story. That is, by looking at the task or project as a whole, we tend to disregard some of the key steps that need to be completed.

How to Overcome the Planning Fallacy

When you’re making a plan and estimating how long it will take, do the following:

1) Ask yourself how long this task, or a similar task, has taken you in the past. If you catch yourself coming up with all sorts of reasons why this time it’s going to be different, and why you’ll be able to complete the task much faster, stop yourself. The amount of time a task has taken you in the past is the best predictor of how long it’s going to take you in the future. Just accept it.

2) Identify the ways in which things might not go as planned. Specifically, come up with three obstacles that could impede your progress. This exercise will help pull you away from a fantasy world in which everything goes as planned, and back into the real world, in which it’s almost certain that not everything will go exactly as you want it to. Beware of unwarranted optimism, and leave some slack time in your schedule to cover any unexpected “incidents”.

3) Write out all the steps you will need to get the task done. Once you see a task broken down into all of its components, you’ll be better able to determine how long the overall task should take. This is a process that Josh Kaufman of The Personal MBA calls, mental simulation.

Conclusion

Another way to understand the Planning Fallacy is to adopt Hofstadter’s Law, which is the following: “It always takes longer than you expect, even when you take into account Hofstadter’s Law.” Take out your to do list and, based on all of the above, re-think how long it’s going to take you to complete each item on the list. Then, start crossing off items.

Now that you know that this cognitive bias exists, you need to start taking it into account when you plan your day, your week, your year, and so on.

Which of the following do you feel best describes you:

• I usually underestimate how long it will take me to complete a project or task.
• I’m very good at estimating how long a project will take.
• I usually get things done faster than I planned for.

Please answer in the comments section. (OK, I’ll go first: I usually underestimate how long it will take me to complete a project or task.)

(Sydney Opera House Close Up” is courtesy of linh_rom)

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• Time Management Secret: Do It Tomorrow
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