You’re an olympic athlete in the javelin throw. You’ve trained hard most of your life, and kept careful records of your distances for some 2,000 practice throws during the last year. It turns out that your distances follow the normal distribution with a mean of 78.82 meters and standard deviation 3.07 meters.
Competition is tough and you’re desperate to win, so you give in to temptation. You start taking a new kind of steroid which improves performance and can’t be detected by the olympic committee’s drug tests. You continue to keep careful records of your practice throws, discovering that the steroids have increased your mean distance by 4 meters.
Come competition time, you’re at your best. You trained hard, got plenty of sleep, ate right, and you were just plain “in the groove.” You’re wearing a new kind of shoe with special cleats designed to give you perfect traction without slowing you down or interfering with your rhythm. Even the weather cooperates, reducing atmospheric friction to a minimum. Everything comes together, all the “natural variation” factors conspire to give you the best performance of your life. Oh happy day! Near day’s end you’re standing on the podium listening to the national anthem, because you won the gold medal with a throw of 89.60 meters — fully 4.2 meters ahead of the 2nd-place throw.
You didn’t just win the gold, you broke the world record (89.58 meters by Jan Železný in 1996; javelins with serrated tails were outlawed in 1991). You’re heralded as a national hero and approached by a well-known breakfast cereal enticing you to sign an endorsement deal for one helluva lot of money. After all, extremes which are that extreme are a big big deal.
That night a sports journalist asks “Why was is so long a throw?” You talk about hard work, proper technique, new training shoes, good weather, and how everything came together at just the right moment. All of which is true.
But the next day the drug tests arrive from the lab. It turns out that the olympic committee has kept pace with the latest in steroid innovations, and the new performance-enhacing drug is detected, no doubt about it. In subsequent investigation, statisticians analyze your careful records of practice throws and demonstrate the surprising increase in your numbers, inexplicable except by cheating. The olympic committee announces that your are stripped of your gold medal and world record, and that you are banned from competition for the next five years.
One of your biggest fans protests that the stats show your drug use only increased your mean distance by 4.00 meters but you beat the 2nd-place throw by 4.2. “He would have won anyway! Give him back his gold! His winning throw wasn’t because of steroids, it was because of a great performance!!!”
There are two things wrong with that claim. First, when we ask “Why was it so long?” we have to include steroids in the list of reasons. Second, it’s downright disingenuous to suggest that there’s some single cause. Yes it was a perfect day, yes those new shoes really did help, yes the weather cooperated, yes you gave a great performance. If you hadn’t worked so hard and so diligently, you wouldn’t even have made it to the olympics in the first place. But steroids increased your chances of throwing the javelin so far, far enough to break the world record, by a factor of more than 60. The fact is that without steroids your throw wouldn’t have been so far.
These days, it’s the weather that’s on steroids. Because of man-made climate change. Cliff Mass’s blog post asks “Why is the Northwest so warm?” Part of the reason — the part that Cliff Mass is desperate to dispute — is global warming.