This makes us miss the mark in completion time
Your estimate will probably be off when you are asked how long a job will take. But when the boss indicates a time frame you could miss by even a wider margin.
It could simply be the time it takes to prepare dinner, or perhaps an extensive project at work. We often try to predict how long it will take to do various tasks. But we’re not very accurate. We tend to be overly optimistic and convinced of our estimates – yet we are often wrong.
A recent doctoral thesis shows that the boss, principal or customer who orders the job, shares some of the blame. We often provide unrealistic time estimates when given figures or signals indicating how long it might take to solve a task. We miss the mark either way – whether the proposed time frame is too large or too small.
The way a question is posed has a big impact on how realistic an answer we give.
The answer is impacted if we are given an estimate of how long a task will take, according to Social Psychologist Erik Løhre at Simula Research Laboratory.
He recently gave his doctoral dissertation on the subject at the University of Oslo’s Department of Psychology.
No matter how unrealistic a proposed time frame is, we tend to select an estimate in the same ball park, so to speak.
“In the worst case, irrelevant time estimates can lead to cost-overruns or unsuccessful projects,” he says.
Watch out when you hire craftsmen
If the boss asks whether you need a month to do a project, you risk giving a confirming answer without having reasoned it out. You face the consequences when you end up taking more time.
- If I ask a plumber to renovate my bathroom, maybe I shouldn’t ask whether it will take a week?
“Exactly. There’s a big risk of a time overrun compared to if you hadn’t suggested anything and simply queried about how much time it will take,” says Løhre.
Psychologists are well acquainted with a mechanism called the anchor effect. Løhre’s study confirms how weighty this effect is.
In a number of trials, software developers were asked to estimate how long it would take to solve various tasks.
Løhre found a remarkably large spread amongst these estimates, depending on how the question was worded to the 381 participants. All were professional software developers.
Twice as long
In one experiment the computer scientists were given a project that involved development of a web-based, searchable library system.
One group was asked whether they thought it would take less than ten hours. They answered that it would take 30 hours.
The control group, which had not been given any suggested times, or anchor, estimated it would take about 60 hours. In other words, they figured it would take twice as long.
“Those who were not given this suggested time of ten hours were probably closer to the truth,” says Løhre.
One or six months?
In another experiment the programmers were asked to calculate how long it would take to develop a web application which displayed various types of information on maps.
The programmers were split into two groups and the question was posed in different ways.
The first group was asked how likely they thought it that the task would take less than a thousand hours. That corresponds to about six months of work for one person. Nearly all answered that this was sufficient time.
When asked to specify a time they estimated an average of 160 hours, or about four work weeks.
A quarter of the time
The control group was given a completely open question about how long they thought it would take to accomplish the same programming job.
Their average estimate was 40 hours – just a quarter of the time quoted by the first group.
“This means that those who were given the so-called anchor value thought the requisite time was higher than in the control group,” says Erik Løhre.
The odds also rise for delays if one tries to suggest a time frame for a project.
“Customers and other employers are smart in refraining from picking unfounded time frames out of their hats when giving assignments,” stresses Løhre.
Of course the issue of who wins and who loses when things take more time or less time than estimated depends on what agreements have been made regarding time overruns. This applies especially with regard to whether a fixed price or an hourly price has been contracted.
Optimists about time
Earlier studies have shown that most of us are optimistic about how fast we can do a job when making an estimate. We think things will go quicker than they actually do. But this doesn’t mean it is wise to use higher anchor values to raise time estimates.
“It’s hardly ever easy to figure out a realistic time estimate. And if people are strongly influenced by the anchor value they can miss the mark in the opposite direction,” says Løhre.
In a test conducted by Løhre’s advisor Magne Jørgensen at Simula, six programming firms were asked to assess the time needed for a job and then given it. A great deal of variation was seen in the estimated times given by the participants and how long the job actually took them.
Earlier studies have generally shown that those who estimate a longer time do indeed spend more time performing the task.
Read the article in Norwegian at forskning.no
Translated by: Glenn Ostling
- Løhre, E., & Teigen, K. H. (2014). How fast can you (possibly) do it, or how long will it (certainly) take? Communicating uncertain estimates of performance time. Acta Psychologica, 148, 63-73. doi: 10.1016/j.actpsy.2014.01.005.