Friday, October 10, 2014

Illusionary Links: Why Spurious Connections are Making You Stupid

by Nomad

The human mind was made to search for recognizable patterns. Generally speaking it has aided the survival of our species. But sometimes, this predisposition can also lead us down the wrong paths.

Riddle me this. 
What is the correlation between the divorce rate in Maine and the per capita consumption of margarine in the United States?  According to the graph below, as less margarine was consumed nationally, the divorce rate in Maine declined. 
Can you guess?

What about this? What could be the connection between the per capita US consumption of cheese and the number of people who died by becoming tangled in their bedsheets? The graph below provides the proof of there is some kind of relationship between the two.
The more people that ate cheese around the country, the more people were found dead  throttled by their knotted bed sheets.

So, what's going on with the dairy products in the US?

And why is there a clear correlation between the marriage rate in Kentucky and the number of people who have drowned after falling out of a fishing boat? 

The graph below strongly suggests that as the marriage rate in Kentucky declined so did the number of people who fell out of fishing boats. 

So have you figured it out yet? The answer is pretty obvious. 
Give up? 
Well, it's a trick question. There's actually no connection between the two things in each of the case. However, all of the graphs do share one connection.  

The above graphs, which can be found at this site, illustrate a common fallacy. Namely, the idea is that a correlation between two variables does not necessarily imply that one causes the other or that one variable is in any way related to the other variable.

Of course, there could be a connection but there doesn't need to be one. It's only a pattern. As a fallacy goes, it's a very seductive one.

The Reasons Why We Believe
Still it's amazing how easily so many people get fooled by this. But then it is not  such a surprise. 
Every week, every day we are routinely bombarded with figures and statistical evidence to prove one thing or the other. Often this evidence can seem pretty convincing, especially when the conclusions supports an idea that we already believe. We are always more ready to accept evidence that supports our prejudices. 

It's a regrettable part of human nature. On top of that, it is also human nature to look for patterns, whether it is seeing dancing elephants in ink blots or imaginary statistical links. Together these two factors work can work against rational thought.

Too often this kind of information provides a lot of filler stories for local news channels or on talk radio. The "factoids" usually begin "scientists have uncovered a link between the number of... and ..."  or "a recent study suggests that people who.." 
Instead of theorizing or attempting to offer a credible reason for the correlation, it is left a scientific mystery. 

Science is all about solving mysteries, that's true, but key part of the scientific method is developing a a hypothesis, based on a careful and rational examination of the facts. The next step is a theory, followed by a means of testing the theory to explain the mystery. 
*   *   *
Generally as misleading as such items are, they are relatively harmless. Because we hear spurious connections all the time, we have become largely immune to this effect. Some critics would say that this constant use of false correlations is damaging the credibility of all science to provide helpful information. The results are a distrust of science in general.

More importantly, however, the fallacy of the spurious correlation is often used in much more deceptive ways.

Biological or Ideological Warfare? 
Take this example from a Media Matters article by Eric Hananoki. 

Conservative media have recently claimed that undocumented children from Central America that surged across the Southern border were in fact a kind of pint-sized delivery system for "biological warfare" and that the deadly strain of enterovirus was the result of this conspiracy. 

That slacker President Obama, they claim, thoughtlessly aided and abetted the wee disease-carrying kids by installing the tykes in public schools. Right next to our vulnerable and tidy tots. Why would he have done such thing? Why would he have taken such a risk? 
According to the conservatives, all because he is "so obsessed with winning the Latino vote." 

(Is he? I thought he was following the strategy of just letting Republican talk away the Latino vote. They done such a good job driving awaythe other demographics.)

To some right wing voters ready to believe any calumny or slanderous allegation against Obama, the coincidental timing of the appearance of this new disease and "those dirty little vagrant kids from God-knows-where" is proof positive that it has to be true. It's common sense. Isn't it? 

Although the disease seemed to appear not long after the surge of illegal children crossed into the US, the facts are a bit more mundane. The disease, according to the Centers for Disease Control (CDC), has been in the country for decades. 

They categorically state there is no link and any attempt to make a correlation is misleading.
Public health experts have debunked the alleged connection between the influx of undocumented children into the United States and the spread of EV-D68. CDC spokesperson Jeanette St. Pierre told Media Matters: "Currently, there is no evidence from testing at CDC that EV-D68 infections in the U.S. are a result of unaccompanied minors moving into the country."
As the article points out Enterovirus was first isolated in the US back in 1962 but this particular strain, was first detected in 1987. That information doesn't come from Rush Limbaugh or Fox News but from Eden Wells, Clinical Associate Professor of Epidemiology at the University of Michigan School of Public Health. She explained to a reporter:
"I think that this really sort of argues against the fact that this is a new virus introduced by anybody."
(If the virus was a weapon in  biological warfare then it was Reagan- not Obama -who fumbled the ball. He had allowed the AIDS crisis to get out of control.)

Sadly the facts and the statements provided by experts will not stop non-experts like Michael Savage, Rush Limbaugh, Pat Robertson and others from spreading misinformation to their listeners. And their listeners- most of whom have long since stopped thinking for themselves- will concur.

The art of rational thinking and the ability to discern what is logical and meaningful within the conservative rank and file is going the way of the dodo bird, the passenger pigeon and the Great Auroch.

So now, what is the connection between eating organic food causes autism? What is that sly Obama up to now?