*Updated with additional sources on 16-June-16*

It is fairly widely known that correlation does not inherently indicate causation. In fact, inappropriately asserting causation is a logical fallacy known simply as a correlation fallacy. Nevertheless, there is a great deal of confusion around this topic, and many people use it selectively. For example, anti-vaccers are adamant that the correlation between in the introduction of vaccines and the decline in diseases is not valid evidence that vaccines work, yet they insist that the supposed correlation between autism and vaccines is 100% proof that vaccines are dangerous. Therefore, in this post I will endeavor to unravel the mysteries of correlation and causation.

Let’s start with basic definitions. Correlation is simply a relationship between two variables. Either they both increase together, both decrease together, or one increases as the other decreases. So, for example, among people under the age of 20, there is…

View original post 1,019 more words