February 26, 2014
Putting Error Bars on Olympic Gold
This past weekend, the 22nd Olympic winter games drew to a close in Sochi, Russia, capping off 16 days of sweat, glory, and tears. Nearly 3,000 athletes from 88 countries competed in almost 100 different events, racing across snow and ice, and astounding the world with feats of power and grace. But on top of its panoply of athletic spectacles, the Olympics provided numerous opportunities for the scientifically-inclined to geek out.
First, organizers had to overcome warm temperatures and subpar skiing conditions by using science to make heaps and heaps of artificial snow (check out the American Chemical Society’s video of the process here). Next, the high-tech suits worn by American speed skaters came under fire for holding back Team USA and allowing the Netherlands to sweep the field (the Under Armour suits have since been exonerated). Then, the women’s downhill — an event usually battled out in fractions of a second — ended in a perfect tie for gold.
That’s right: Dominique Gisin (from Switzerland) and Tina Maze (from Slovenia) each completed the 2 mile-long course in 1 minute, 41 seconds and 57 hundredths of a second. Except…not exactly. As the New York Times reported after the event, the race clock actually measured the skiers’ times out to four decimal points (the ten thousandths place), which would surely reveal a small difference in the two women’s times. But the International Ski Federation (FIS) stipulates that race times be rounded to the nearest hundredth — no more, no less — because even Olympic results are subject to scientific uncertainty.
Scientific uncertainty is a tricky concept, so it is often the source of much…well…uncertainty. Luckily, this Olympic coincidence provides a perfect real-world opportunity to discuss what scientific uncertainty is and why it’s important.
Perhaps because we often use the word “uncertain” in everyday speech to describe things we don’t know or understand (like next week’s weather, or the meaning of a cryptic poem), it’s natural to assume that scientific uncertainty implies that we don’t know or understand scientific results. In fact, the opposite is true: scientific uncertainty tells us exactly how well we know the things we know.
For example, it’s clear from the results that we actually know Gisin and Maze’s times very well. The fact that their results are subject to scientific uncertainty does not undermine our confidence that both women skied the course in 1:41.57. It means that we cannot know if one skied it in 1:41.572 and the other in 1:41.573. That’s because the timers and judges who organize the race have determined that times simply cannot be measured that precisely. “When you start getting into such small numbers you cannot guarantee the integrity of that number,” said a FIS representative said in a recent interview with the New York Times. For simplicity, officials just round the time to the nearest hundredth.
The danger of reporting Gisin and Maze’s gold medal race times to the thousandth and ten thousandth places is that doing so might incorporate effects unrelated to the skier’s performance. For instance, one skier might have appeared slower because a fleck of snow interfered with the laser beam used to time the finish, or because a surge of electricity momentarily affected the clock. After accounting for outside factors like this, race officials can calculate the uncertainty inherent in timing how long it takes for a skier to travel between the starting line and the finish. This uncertainty is less than a hundredth, but more than a thousandth. But that doesn’t stop the clock from displaying these extra digits all the same. And this is the whole reason we need the concept of scientific uncertainty: we can easily calculate scientific results more precisely than we can know them.
Scientists (and Olympic officials) want to be very clear about exactly what they know and what they don’t. By eliminating the unreliable decimal points from the racers’ times, officials ensured they did not give the gold to the wrong skier. Instead, Gisin and Maze made Olympic history as the first skiers to tie for first. Well…almost.
Learn more about the nature of scientific knowledge in our module.
Learn about the role of uncertainty in climate science from the Union of Concerned Scientists.
Read this article from The Humanist about how uncertainty affects public perception of scientific issues.
Written by Julia Rosen
Julia Rosen is a freelance science writer and PhD student at Oregon State University. She received a Bachelors degree in Geological and Environmental Sciences from Stanford University before beginning her doctoral research on polar ice cores and climate change. In between, she did her Master's in backpacking around the world and skiing. Julia is a periodic contributor to Oregon States research magazine, Terra, and helps write blog content and develop learning modules for Visionlearning.