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The History of 'Correlation Does Not Imply Causation'
Dr Herbert West writes "The phrase 'correlation does not imply causation' goes back to 1880 (according to Google Books). However, use of the phrase took off in the 1990s and 2000s, and is becoming a quick way to short-circuit certain kinds of arguments. In the late 19th century, British statistician Karl Pearson introduced a powerful idea in math: that a relationship between two variables could be characterized according to its strength and expressed in numbers. An exciting concept, but it raised a new issue: how to interpret the data in a way that is helpful, rather than misleading. When we mistake correlation for causation, we find a cause that isn't there, which is a problem. However, as science grows more powerful and government more technocratic, the stakes of correlation — of counterfeit relationships and bogus findings — grow larger."
Correlation doesn't PROVE causation.... ...but it bloody well DOES suggest it, at least in the course of our daily lives.
The reason this phrase is so catchy is that it's counter-intuitive, and easily proven to be true. People love to use it as a "gotcha" phrase, PRECISELY because in regular life correlation does in fact usually imply causation.
In fact, correlation is used by most scientists to begin the hypothesis process. A power plant is built on a river, and the river starts drying up - most people would begin their analysis by checking on the power plant, and not the population of honeybees.
Your kid is alone in the kitchen. The cookie jar is (now) empty. Does his presence CONCLUSIVELY PROVE that he ate the cookies? Of course not, and a wise parent would find other evidence to draw a conclusion. But the correlation of their places in time and space, as well as a known predilection for cookies means that correlation strongly suggests an avenue of investigation (you're probably not going to start figuring out what happened by pursuing some other entirely different course).
It's the sort of empty-headed 'gotcha' phrase that's so popular and so often used without real thought behind it.
-Styopa
How about Correlation is insufficient to PROVE causation
I had the phrase "Desired: A woman who understands that correlation does not imply causality..." in my dating profile.
I married the woman who replied. Yes, I am surprised that worked as well.
Kind thoughts do not change the world
The correlations are NOT "false". The relationships between the numbers are (almost always) NOT "conterfeit".
"Correlation does not imply causation" means exactly that. If the sky is dark and people are carrying around umbrellas, this does NOT imply that darkness causes umbrellas, or that umbrellas cause darkness. The causal relationship between two numbers is not determined by how often one number changes at the same time as another.
To put it another way: correlation is an *observed* behaviour, causation is a *tested* behaviour.
-- 'The' Lord and Master Bitman On High, Master Of All
My statistics professor called these "lurking variables". Something might exist to cause both elements in a correlative relationship, but if it's not being considered in the analysis, the analysis of the correlation will be misleading. Yours is a great example.
Nice, but how bout correlation is a math formula, on the other hand causation has a ten page philosophical wikipedia page and even though Hume died like 300 years ago this year people are still arguing about it, with the exception that on the internet everyone agrees correlation isn't it, which I guess is at least some progress.
The reason causation has a ten page philosophical page is that on the macro scale everything is a result of and happen in conjunction with a gazillion butterfly effects that were either present or absent, in fact the physical article is quite short. Imagine for a murder every detail that happened in both the murderer's and victim's life who lead them there, they're all causally necessary but we put the blame on the killer. Not the policeman who forgot his bulletproof west at home or the kids who teased the murderer in third grade or the parents for conceiving him. It tries to give weight and quality to those causes that depends on the state of mind, say attempted arson is a lot more "dominating" relative to poor fire safety than an accident even if the fire is physically identical. And it all depends on how well the person could predict or control the chain of effects set in motion.
Causality is easy. Causal responsibility - which by the way is not just about assigning blame, but also things like credit - is very hard. For example, you are hanging off a cliff and another person clings to you but you can't hold on. Either you kick him off so he falls to his death or you both fall to your deaths. In no case is there a question of physical cause and effect, but would you philosophically cause his death by kicking him off or was he dead either way? What if you can hold on another minute, is that murder? Five minutes? Fifty years? I mean he's human, he's eventually going to die - you're not really changing the outcome. What if you're 100% sure you can pull yourself up, but only 99,9% sure you'll both fall to your deaths and a 0,1% chance that you through superhuman strength will pull you both up? It's hard not to get philosophical.
Live today, because you never know what tomorrow brings