As the above graph clearly shows, the number of reported autism cases in the United States directly correlates with the size of the Internet.
Holy crap! The Internet is causing autism!
How can those rich brainiacs at Google and Microsoft sleep at night, knowing their technology is somehow polluting our children’s bodies with dangerous toxins? At this rate, by 2068 every single person in America will have autism! This is an outrage!
Why haven’t the major news networks caught on to this? Obviously they are in bed with the big pharmaceutical companies who want this information suppressed from the public eye!
Email your relatives and spread the word! Don’t use the Internet!
Alright, settle down.
But the data appears to make a very good case, doesn’t it? The size of the Internet is strongly proportional to the number of autism cases in the United States. This much is true. But I can just as easily make the claim that autism is linked to hybrid car popularity, gas prices, global warming, or Souja Boy album sales.
What we have here is a classic example of a common and potentially dangerous logical fallacy known as “cum hoc ergo propter hoc” or “false cause”. To echo the tired statistical adage, “correlation does not imply causation”.
When I was in high-school and driving for the first time, I quickly started to notice something very peculiar. Occasionally while driving, I would see street lights suddenly flicker on and off in my presence. I was intrigued, and started paying more and more attention to this.
It became so prevalent that I was able to actually predict when certain lights would turn off. I would frequently joke with my passengers, claiming I had some sort of “Powder”-like mental phenomenon.
“See that street light over there? Just a sec – I’ll turn it off.” And ‘bzzzt’, in a few seconds it would turn off. It was fun, chicks dug it, but secretly I knew I didn’t have any special powers. It’s all science and statistics!
Years later I discovered that SLI (street light interference) is actually a very common paranormal belief. Subscribers believe “SLIders” have the ability to turn on and off common street lights and other fluorescent lights using a hidden mental power. Apparently I was unknowingly part of a growing and powerful underground group of psychomentalists, whose only power is to annoy nighttime bicyclists.
The anticlimactic truth is that street lights go through a natural “cycling” phase as they age. Coupling this with faulty or oversensitive sun-light sensors and you have yourself a crack-pot theory. The narcissistic SLI affect is further amplified by something called “confirmation bias”, the tendency to only retain evidence to support an already accepted hypothesis.
Confirmation bias is sneaky. Psychics and alternative medicine pushers just love to use this common logical fallacy to their advantage. In fact, investigator James Randi in a 1991 study of psychic power found that people tended to maintain a strong selective memory toward psychic “hits” and tended to forget or ignore incorrect psychic predictions. You can easily extend this idea to tackle most paranormal or supernatural phenomena. (One of these days I’ll write a post on “Bible Codes”. In my undergrad I wrote a “Bible Code” program in MATLAB – unsurprisingly there are just as many interesting “hits” in Harry Potter as in King James.)
The lesson here is to not haphazardly assume an inferred explanation from your data. In the example of SLI, a simple test would show that only a handful of specific street lights flicker, and that they continue to flicker whether or not a “SLIder” is present. Science may be a downer sometimes, but no one guaranteed the truth was exciting.
It can be especially difficult at times to not fall victim to these kinds of logical fallacies; most modern superstitions are a result of “false cause” and “confirmation bias”. But how do you recognize them?
Consider one of my favorite “false cause” examples: “Sleeping with your shoes on causes headaches.”
Kinda makes sense. In fact, if you pay attention you’ll notice this observation might indeed seem true based on your own personal experiences. The last time you woke up with shoes on, did you have a headache? Some of you are nodding. But there’s a hidden factor here, isn’t there? Alcohol intoxication. A late night with Jack Daniels is going to increase both your chances of sleeping in your shoes and waking up with a hangover. The two resulting consequences are certainly related, but only indirectly through a common variable.
Need another example? I recently saw a TV ad for Stouffer’s microwavable lasagna that went like this:
“Studies show that kids who have regular family dinners tend to get better grades. Stouffer’s Easy Express is ready from the microwave in under 20 minutes. So you can make something that’s good … in so many ways.” Yikes. This one makes a couple of mistakes.
The ad’s message is that kids who eat family dinners get better grades, therefore buy Stouffer’s microwave lasagna and your stupid kid won’t fail algebra. Really? I can just see the concerned mother explaining to the school’s counselor: “I don’t understand why he’s still failing! We eat a lasagna family dinner every night! Should we try the meatloaf?”
The two beneficial consequences, family dinners and good grades, are most likely the result of a linking variable, like a strong, healthy family life. A kid who’s running around the Taco Bell parking lot every night to avoid his drunken step-dad and drug-infused mom probably isn’t going to study for tomorrow’s biology test. (Ironically, if Stouffer’s had a true claim here, you kid’s chem grades would probably rise as their gym grades fell.)
But what if there is no linking variable? Like my autism/Internet link, some things appear to be related, but simply aren’t. The connection, even one that is extremely complex, might be nothing but a chance coincidence. The satirical religion Pastafarianism parodies this fallacy with their hilarious implication that “with a decrease in the number of pirates, there has been an increase in global warming over the same period. Therefore, global warming is caused by a lack of pirates.” Makes you appreciate BitTorrent a little more, doesn’t it?
Unfortunately, it is very easy to make incorrect and erroneous conclusions regarding some very important issues. Medical science is not immune to this. (I make funny.)
Despite claims by very vocal celebrities like Jenny McCarthy and Jim Carrey, there actually has not been a scientifically proven link between autism and childhood vaccines. People like McCarthy will jump at the chance to brandish a graph showing a correlation between Thimerosal usage and autism rates. But like so many others before her, McCarthy is making a very large logical fallacy.
This normally wouldn’t be that big of a deal to me; I see people make logical fallacies almost every day. But thousands of concerned parents aren’t getting their children vaccinated based on these false claims. Now this actually is a serious issue!
So the overall lesson is to keep those wits sharp. Apply your data responsibly. And for crying out loud, vaccinate your kids!
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