3 ms·

Unfortunately there are too many useful rhetorical devices in the list, devices that serve a purpose. Ironically, the list starts off with "correlation is not c

by lutusp 13y ago

Unfortunately there are too many useful rhetorical devices in the list, devices that serve a purpose. Ironically, the list starts off with "correlation is not causation," an expression that in most cases is raised for very good reasons -- for example, any popular science story that includes the word "linked" but without adequate qualifiers. If more people were science-literate, these platitudes wouldn't be necessary. But they aren't, so they are.

TelmoMenezes 13y ago
I agree. The author says "If there's some specific reason you think a a study is wrong, describe it". Unfortunately, this is very often precisely the problem: many times not in the study itself but in the way it's reported. "Correlation is not causation" mistakes are not always obvious. Especially when there's ideological bias. E.g: the claim that owning a gun increases the chances that you will be violently killed by X%.
- lutusp 13y ago
  > The author says "If there's some specific reason you think a a study is wrong, describe it". Unfortunately, this is very often precisely the problem: many times not in the study itself but in the way it's reported. Too true. My recent favorite was a popular account of a marijuana study. The popular article was titled "Marijuana causes psychosis" or words to that effect. The popular account went on about how teenagers went crazy after smoking killer weed. The study itself said, "We don't know whether marijuana use sometimes causes psychosis, or psychosis sometimes causes marijuana use. More study is needed."
chilldream 13y ago
"Correlation is not causation" started useful but has become less useful the more cliched it became. And OP is right that it's particularly useless among people who've already heard it. The whole reason people felt the need to mention "correlation is not causation" is that correlation is evidence of causation. Some people seem to think this catchphrase means the two are unrelated which is also false.
- lutusp 13y ago
  > The whole reason people felt the need to mention "correlation is not causation" is that correlation is evidence of causation. No, without evidence that assumption is false. Correlation can only be evidence for an unexplained link, and even that is often undermined by desperate researchers' predisposition to offer any detected correlation as though it couldn't result from chance. Given A and B, absent a plausible causative mechanism, and a correlation between them, possible explanations include: * Chance -- quick, publish! * B caused A. * A caused B. * An unevaluated cause C connects A and B. If this seems to go to extremes in skepticism, well, remember that skepticism of new results is -- or should be -- the scientist's job. Example: http://www.nature.com/nature/journal/v483/n7391/full/483531a.html http://www.nature.com/nature/journal/v483/n7391/full/483531a... Title: "Drug development: Raise standards for preclinical cancer research" Quote: "Fifty-three papers were deemed 'landmark' studies (see 'Reproducibility of research findings'). It was acknowledged from the outset that some of the data might not hold up, because papers were deliberately selected that described something completely new, such as fresh approaches to targeting cancers or alternative clinical uses for existing therapeutics. Nevertheless, scientific findings were confirmed in only 6 (11%) cases. Even knowing the limitations of preclinical research, this was a shocking result." > Some people seem to think this catchphrase means the two are unrelated which is also false. But without evidence, without a rigorous scientific evaluation, that's a scientist's default assumption, an assumption that relies on the null hypothesis. Using the null hypothesis, one assumes there's nothing there, that the association between A and B results from chance, then looks for reliable evidence that might lead us to a different conclusion.
  - chilldream 13y ago
    > No, without evidence that assumption is false. Correlation can only be evidence for an unexplained link I did not say it was conclusive evidence; I said it was evidence. I'm well aware that "A is correlated to B" does not prove "A causes B" or even "A causes B or B causes A", but it is a data point in favor. Saying "We should evaluate other evidence before we decide if A causes B" is reasonable skepticism. Acting as though "A is correlated to B" has no bearing whatsoever on the question of whether A causes B is another matter. (Not that I actually disagree with most of your post, mind you! The real message of "correlation is not causation" is "don't overrate this specific data point; it's a common mistake". But the realist shouldn't underrate it either.)

by lutusp 13y ago

TelmoMenezes 13y ago

I agree. The author says "If there's some specific reason you think a a study is wrong, describe it". Unfortunately, this is very often precisely the problem: many times not in the study itself but in the way it's reported. "Correlation is not causation" mistakes are not always obvious. Especially when there's ideological bias. E.g: the claim that owning a gun increases the chances that you will be violently killed by X%.

lutusp 13y ago
> The author says "If there's some specific reason you think a a study is wrong, describe it". Unfortunately, this is very often precisely the problem: many times not in the study itself but in the way it's reported. Too true. My recent favorite was a popular account of a marijuana study. The popular article was titled "Marijuana causes psychosis" or words to that effect. The popular account went on about how teenagers went crazy after smoking killer weed. The study itself said, "We don't know whether marijuana use sometimes causes psychosis, or psychosis sometimes causes marijuana use. More study is needed."

chilldream 13y ago

"Correlation is not causation" started useful but has become less useful the more cliched it became. And OP is right that it's particularly useless among people who've already heard it. The whole reason people felt the need to mention "correlation is not causation" is that correlation is evidence of causation. Some people seem to think this catchphrase means the two are unrelated which is also false.

lutusp 13y ago
> The whole reason people felt the need to mention "correlation is not causation" is that correlation is evidence of causation. No, without evidence that assumption is false. Correlation can only be evidence for an unexplained link, and even that is often undermined by desperate researchers' predisposition to offer any detected correlation as though it couldn't result from chance. Given A and B, absent a plausible causative mechanism, and a correlation between them, possible explanations include: * Chance -- quick, publish! * B caused A. * A caused B. * An unevaluated cause C connects A and B. If this seems to go to extremes in skepticism, well, remember that skepticism of new results is -- or should be -- the scientist's job. Example: http://www.nature.com/nature/journal/v483/n7391/full/483531a.html http://www.nature.com/nature/journal/v483/n7391/full/483531a... Title: "Drug development: Raise standards for preclinical cancer research" Quote: "Fifty-three papers were deemed 'landmark' studies (see 'Reproducibility of research findings'). It was acknowledged from the outset that some of the data might not hold up, because papers were deliberately selected that described something completely new, such as fresh approaches to targeting cancers or alternative clinical uses for existing therapeutics. Nevertheless, scientific findings were confirmed in only 6 (11%) cases. Even knowing the limitations of preclinical research, this was a shocking result." > Some people seem to think this catchphrase means the two are unrelated which is also false. But without evidence, without a rigorous scientific evaluation, that's a scientist's default assumption, an assumption that relies on the null hypothesis. Using the null hypothesis, one assumes there's nothing there, that the association between A and B results from chance, then looks for reliable evidence that might lead us to a different conclusion.
- chilldream 13y ago
  > No, without evidence that assumption is false. Correlation can only be evidence for an unexplained link I did not say it was conclusive evidence; I said it was evidence. I'm well aware that "A is correlated to B" does not prove "A causes B" or even "A causes B or B causes A", but it is a data point in favor. Saying "We should evaluate other evidence before we decide if A causes B" is reasonable skepticism. Acting as though "A is correlated to B" has no bearing whatsoever on the question of whether A causes B is another matter. (Not that I actually disagree with most of your post, mind you! The real message of "correlation is not causation" is "don't overrate this specific data point; it's a common mistake". But the realist shouldn't underrate it either.)