# Correlation does not imply causation

## Correlation does not imply causation

Here's why and what you should know about it.

It is a common misunderstanding to assume that one thing is the consequence of another because they happen together.

People do it all the time.

Sometimes, they don't do it on purpose, they just don't see the difference or make an error.

Sometimes, they highlight correlation to falsely imply causation, which is simply dishonnest.

In any case, thinking that correlation implies causation is incorrect.

Let us be clear. Things may happen together because one is the consequence of the other. So, people are right when saying that correlation may be a hint of causation.

Nonetheless, one has to be careful and rigorous. A lot of things happen together, even though they do not cause each other. For example...

A study showed that for French kids, being named Kevin was correlated to getting poor grades in school. Of course, your name does not have a direct effect on your grades. In that case, the correlation is caused by a common source.

See the comments under that graph showing the correlation between the person being CEO of Microsoft and the stock price and the analysis here for another example of a correlation not being a proof of causation.

Try to figure out if there is a causation effect, and if so, in what direction, in this article about the correlation between sexual activy and salary.

So what?

Well... just keep that in mind and learn to detect and point at fallicious arguments like the ones discussed here. It will be useful on a daily basis:

• Making sound arguments (i.e. explaining real cause to effect, not relying only on correlation) will make you more credible.
• Having the ability to detect false reasoning will help you be a better critic of what you hear and read.
• Helping people around you understand the above will enrich them and give you warm fuzzies.

Let people around you know when you hear a weak argument based on correlation. Be a constructive critic, and help us make the world a better place.

Thank you.

## Want more?

There are good articles to learn more on Wikipedia and on RationalWiki.

You can find some humor on the topic on XKCD and Gizmodo.