I shed an invisible tear whenever I hear “correlation does not imply causation” which the otherwise excellent swivel (a website about correlations) emphasizes. Of course, there’s truth to it. It saddens me because:
1. It’s dismissive. It is often used to dismiss data from which something can be learned. The life-saving notion that smoking causes lung cancer was almost entirely built on correlations. For too long, these correlations were dismissed.
2. It’s misleading. In real life, nothing unfailingly implies causation. In my experience, every data set has more than one interpretation. To “imply” causation requires diverse approaches and correlations are often among them
3. It’s a missed opportunity — namely, an opportunity to make a more nuanced statement about what we can learn from the data.4
4 It’s dogmatic (see “Jane Jacobs on Scientific Method”). Some correlations, such as those from “natural experiments,” imply causation much more than others. I suspect it does more harm than good to lump all of them together.
Addendum: After I posted this on my blog (blog.sethroberts.net) someone from swivel.com commented that I was right and that he would remove the phrase from their site.
Correlation --> Causation rolls easily off the tongue. Getting a consensus is big in science these days, so just let people vote. More often than not, does correlation imply causation? I bet it does.