#2. What They're Calling an "Epidemic" May Actually Be Random Chance
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Sounds Like ...
Studies show that people who live near power lines have a higher rate of cancer and other diseases! That means electricity is quietly killing you from within! It's a good thing that right this minute, your face isn't near any glowing devices that run on electricity ...
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"You kids get down from there, you'll catch the cancer!"
The Problem Is ...
The "power lines cause cancer" thing was a real study that caused real panic not too many years ago. They looked at a map, drew a circle around people who lived near power lines, and looked up what diseases those people had. Sure enough, it wasn't hard to find neighborhoods just chock full of tumors.
But in doing so, they fell victim to what is called the Texas sharpshooter fallacy, or the clustering illusion -- that's when you see false patterns in random data. The name alludes to a theoretical cowboy who shoots randomly at the side of a barn, then paints a target wherever the most shots are clustered together and tells people he's a sharpshooter.
In England, they call it the "throw a girl in front of the tennis ball machine" fallacy.
The truth is that in a large enough population, you're going to get random patterns -- especially if you give yourself infinite room to find similarities. For instance, the above study may also have found that kids living near power lines are 5 percent more likely to be named "Steve," or that they are 3 percent more likely to prefer red bicycles. When you're talking about tiny differences, you can find all sorts of weird-ass connections. So, they found that in some areas, kids were up to four times as likely to have leukemia (holy shit! Power lines are murdering our children!), but they ignored the fact that in other areas, the kids were actually less likely to have it (holy shit! Power lines have magical healing abilities!). In reality, it was all averaging out.
And if you just found yourself saying, "Yeah, but with those kids who were four times as likely to get sick, there has to be something to it," you've already forgotten at least two of the points in this article (hint: leukemia is rare and it doesn't take many cases to get a fourfold increase).
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"Again we boo! Boo for a second time, mathematics!"
Why Does It Matter?
Remember that crazy story about the guy in Miami who went insane and ate another dude's face off? Then every day after that, there was another story of a biting attack? Even the skeptics were all "Wow, another crazy person bit somebody on the subway! There has to be something to this."
And there was: When humans get into fights, we tend to bite each other, but only in the wake of the Miami thing was there any reason for such incidents to become news -- the only thing that changed was that suddenly every bite became a headline. We started looking for a pattern, and there it was. Then we quickly got bored with it, even though right now somebody, somewhere, is biting someone else.
And not all of them are the victims of emotionally disturbed parents.
Over the centuries, this fallacy has caused us to invent entire epidemics out of whole cloth. Hell, this is even thought to be one of the reasons for the "witch hunts" that took place throughout history (or, you know, today) -- everyone in the neighborhood suddenly got sick, there's a weird woman living in the neighborhood, therefore said woman must have caused the sickness using her devil magic.
Now, sometimes the trend is in fact real, but caused by something totally unrelated. That brings us to the biggest fallacy of them all ...
#1. Correlation Does Not Equal Causation
Sounds Like ...
The media love to report on the latest scientific study that tells us what's going to kill us today. According to this report on a study about the effects of television on health, scientists are stunned to discover that watching TV is as bad for you as smoking cigarettes after finding that every half hour of TV you watch after the age of 25 shaves a whopping 11 minutes off your life. But how can we possibly cut down when there are six whole shows about baking cakes?
Or, you may have run across someone who still believes that vaccines cause autism in children -- they may even have incredibly convincing line graphs showing that, yes, as the rate of vaccination has gone up, so has the rate of autism diagnosis. How can you argue against graphs?
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"As you can see, mathematically, you are a piece of shit and you totally deserve the slap I'm about to whip at you."
The Problem Is ...
If you know anything about how a television works that doesn't involve the word "sorcery," then you'll notice that it's just a box of lights and wires. It's difficult to understand how a benign pile of electronics can suck your life force out of your body from the other side of the room. And that's the problem -- the article is reporting on a causation, when all it really has is a correlation.
The difference is that until you know how television is murdering you, all you know is that television and death are related in some way. There's no way to tell whether watching a lot of television and dying a little earlier are both symptoms of something else.
Of course, it could be more of a case of where you're watching TV.
And that, by the way, seems to be exactly what's going on here -- it turns out that people who don't like exercise tend to reach for hobbies that don't involve moving (like television), and not getting enough exercise is what's killing us. Which is to say, reading a book is much more deadly than watching TV on a stationary bike.
Another well-known example is the myth that kids who eat breakfast perform better at school. It's true that the statistics do show a correlation between eating breakfast and higher academic achievement, and this in turn led to parents cramming cereal down their children's throats in the hopes of force-feeding them into college. But when the phenomenon was finally investigated, researchers found that the act of eating breakfast really didn't affect the kids' intelligence at all. It's just that the type of kids who have things going on in their lives that keep them from eating breakfast are also the type to have trouble at school.
"Bring in one freakin' flame thrower for show and tell, and everyone gets all uppity about rules."
Why Does It Matter?
It wouldn't, if the only result was increased waffle sales during school months. But shit gets serious when we start misidentifying the cause of society's problems. Like if, say, we decide that life-saving vaccines are causing autism when in reality the number of kids being diagnosed with autism rose not with the rate of vaccinations, but with our ability to detect autism. To demonstrate this, opponents to the vaccine hysteria whipped up another graph:
Please don't tell Jenny McCarthy about this.
Nathaniel lives on a boat, where the only statistic he has to deal with is the frequency of pirate attacks. James has a degree in physics and chemistry, and you can follow him on Tumblr, where he talks about neither.
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