I was going through the news yesterday, when I found an article whose headline read something like NUTRASWEET CAUSES CANCER!! Holy crap! I do not want to get cancer!! I drink a ton of diet soda! I better read this article. In the article it referenced a study that was recently done. As some of you who read this blog know, I am not a normal person... I do things the normals just do not do. I clicked on the reference and read the study.
It turns out that the study was not really a legitimate study. It was a statistical correlation study. What is that? It is a method where you can take many different and seemingly unconnected variables and see how they correlate with one another. A correlation coefficient of +1 means they are very correlated, conversely a correlation coefficient of -1 means that they are not correlate at all.
The study that the article was written on showed that the correlation between those that consume NutraSweet and those that get cancer had a reasonably high correlation coefficient.
What does all that mean? NOTHING!! Correlation studies are the epitome of junk science. When researchers are looking for something to study, they often do these correlation studies so that they can find something that may be interesting or impacting to work on. The problem starts when a researcher needs to have something published to keep his job. This is a way he can be polished and make a big stink in the media because not very many people know what a correlation study even is. Thus we get idiotic headlines that have no basis in statistics or science.
Be careful what you read, be sure that it means what you think it means.