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That's a common misinterpretation of "correlation does not imply causation". It'd be more accurate to say "correlation implies causation but the direction of ca

by Zarel 12y ago

That's a common misinterpretation of "correlation does not imply causation". It'd be more accurate to say "correlation implies causation but the direction of causation must be derived separately." If there's a real correlation between A and B (i.e. the correlation isn't a coincidence), that must mean that either A causes B, B causes A, or a third factor causes both A and B. In context, since we know that femaleness is (barring certain rare disorders) caused by the sex chromosome of the sperm that reaches the egg, which is essentially random, we can be fairly sure that it's not caused by school grades or anything that would affect school grades, which does allow us to conclude with a reasonable degree of confidence that femaleness (indirectly, of course) causes higher grades.

alasdair_ 12y ago
> If there's a real correlation between A and B (i.e. the correlation isn't a coincidence), that must mean that either A causes B, B causes A, or a third factor causes both A and B. How can you ever tell that the correlation isn't a coincidence? (see: pirates are correlated with global warming http://sparrowism.soc.srcf.net/home/pirates.html http://sparrowism.soc.srcf.net/home/pirates.html) that seems a bit hand-wavey. "Oh, that's not a REAL correlation..." sounds a bit like "Oh, that's not a TRUE Scotsman..."
- Zarel 12y ago
  Pirates being correlated with global warming isn't a coincidence; pirates decreasing and global warming are both (indirectly) caused by the Industrial Revolution. It's true that you can never be completely sure that any correlation isn't a coincidence, just like you can't be sure that the sun will rise tomorrow. You can, however, be sure beyond a reasonable doubt with enough of a sample size and a strong enough correlation. Out of curiosity, do you personally believe it's likely (say, >5% chance) that it's a coincidence that girls have better grades than boys?

by Zarel 12y ago

alasdair_ 12y ago

> If there's a real correlation between A and B (i.e. the correlation isn't a coincidence), that must mean that either A causes B, B causes A, or a third factor causes both A and B. How can you ever tell that the correlation isn't a coincidence? (see: pirates are correlated with global warming http://sparrowism.soc.srcf.net/home/pirates.html http://sparrowism.soc.srcf.net/home/pirates.html) that seems a bit hand-wavey. "Oh, that's not a REAL correlation..." sounds a bit like "Oh, that's not a TRUE Scotsman..."

Zarel 12y ago
Pirates being correlated with global warming isn't a coincidence; pirates decreasing and global warming are both (indirectly) caused by the Industrial Revolution. It's true that you can never be completely sure that any correlation isn't a coincidence, just like you can't be sure that the sun will rise tomorrow. You can, however, be sure beyond a reasonable doubt with enough of a sample size and a strong enough correlation. Out of curiosity, do you personally believe it's likely (say, >5% chance) that it's a coincidence that girls have better grades than boys?