#3 The One About The Planning Fallacy

Why do things often take longer than we think?

Every four years we hear stories of host cities rushing to finish their preparations for the Olympics, the weekly grocery shop always seems to take ages, and as sure as clockwork, many students will cram a lot of their homework or revision for a test into a short space of time just before it has to be submitted.

Keen to answer this question, researchers from Canada Roger Buehler, Dale Griffin and Michael Ross ran a series of studies. They asked students to make predictions about how long various pieces of coursework, assignments and tasks would take to complete, and then measured how accurate they were and under which conditions students were most effective at fulfilling their predictions.

the main findings

#1 Over 70% of students finished their assignment later than they had predicted they would, with the average time taken being over 55 days compared to the average prediction of 34 days.

#2 In the second study, the researchers found a similar number of people underestimated the time it would take to complete a task, regardless of it if was an academic piece of work or an everyday activity, such as cleaning their apartment or fixing their bike.

#3 60% of students who spent time actively recalling similar previous tasks were more likely to accurately predict how long the next task would take. Students who did not use this technique were only right 29% of the time.

#4 When making future predictions, students were more likely to think about future progress instead of potential future obstacles.

#5 Students were more likely to finish a task on time if the deadline was set for them, rather than setting one themselves.

related research

There has been a lot of research around the importance of setting of both goals and deadlines. Setting goals can help students focus their attention, minimise distractions, enhance work ethic and persistence.

Likewise, setting regular deadlines has been found to help students manage their time and energy over the course of the year as well as improving overall grades. This is because the further away a deadline seems, the less impact it has on people’s attention, which subsequently reduces how well they spread out their efforts.

Other research to help people better manage their time has revolved around minimising procrastination. One popular strategy to do this includes just doing the task for a few minutes, as actually starting a new project is half the battle. Other techniques include improving self-regulation, so that students are less likely to get distracted, as well as doing the hard and important tasks early in the day as you probably have more energy then than compared to late at night.

classroom implications

As students get older, there is more of an emphasis on managing their own time and taking more responsibility for their independent study. Clearly, managing their time is an important skill needed for this, as is making estimations on how long different tasks will take.

Results from this study suggest that there are two key things that teachers can do to better help students make more accurate predictions. The first is to break a task down and set short regular deadlines for them. The second is to help them make clear explicit comparisons to previous similar tasks they have done. Helping them draw similarities and distinguish differences, as well as reflecting on how long these tasks took will help improve their planning time.

The researchers of this study offer a word of warning on this though, noting that “it seems that people can know the past and yet still be doomed to repeat it”. Shakespeare’s Macbeth is a good example of this. Teachers can play a key role in helping their students learn from their previous mistakes. Indeed, the researchers state that “individuals will generate more realistic and accurate predictions if they take past completion times into account. This improvement in prediction should only occur, however, if participants’ recollections are valid and if their present task is comparable with the projects that they recall”. Teachers can offer a guide sense of perspective and guidance on this.