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I think that all of these arguments are pivoted off the same idea. Roughly, but not exactly(): (Co-)existence is necessary for correlation Correlation
by tel 12y ago
I think that all of these arguments are pivoted off the same idea. Roughly, but not exactly():
(Co-)existence is necessary for correlation
Correlation is necessary for causality
Or maybe (E > Co > Ca). What this means is two-fold
1. It's valuable and common to note E and Co
suggestively of Co and Ca respectively. If
I *notice* E then I begin to hypothesize about
Co because I know have evidence for its
possibility if not yet evidence for Co directly
2. Being lazy/imprecise in speech or reasoning
might cause someone to "skip a step" and claim
something more powerful than what they actually
have.
With regard to (1), I think it's completely valuable to make these observations. At their heart, they're nothing more than broadcasting and contextualizing data* and that's an important function. So (2) is where all of the danger lies---properly contextualizing data and what it actually gives credence to.
So how can we make sure that (2) occurs casually without precluding (1)?
I think that articles like this one and all around the whole "correlation is not causation" tagline are great. They help to ensure people remember the size of the space between each step in E > Co > Ca.
I think another powerful technique would be to demonstrate more arguments that make the jumps and highlight the properties which allow that to happen. Chris did a good job here demonstrating correlation—what it looks like when it exists or fails to exist—but much, much more can be said about the E > Co jump.
The Co > Ca jump is far more complex. Worse, it's often obscured through opaque words like "randomized, controlled study" or "scientific method" which are actually quite far away from the mechanisms which allow that jump to be made—they're more like implementation details obscuring a great API. Demonstrating clear arguments here (and not "rain + wet grass" oversimplified ones) could be a great boon to public reasoning.
What else can be done to reduce (2) without precluding (1)?
(*): Really (linear) correlation is just one kind of relationship-of-interest between things. This is often pointed out when people talk about correlation in terms like "circular relationships have 0 linear correlation, oh no!"
What I'd like to write instead might be E > M > C where M becomes "model building". Choosing to highlight linear correlation means that you're choosing a linear model. That might be perfect, or it might be wrong, but you still must choose it before you can structure your observations into evidence of some kind of causality. Generally, at this point, you would also want to begin developing covariates all in preparation for the C step.
- conistonwater 12y agoBear in mind that causality does not imply correlation. (I know I'm arguing with just one sentence in your post, but I think it needs to be pointed out.) Sometimes you are observing controlled variables, in which case an counter-example like Friedman's thermostat will disprove this notion.
- tel 12y agoYeah, I would like to leave "correlation" out of it entirely. The real steps are more like "model building" and "evidence collection", but those are both more complex and not common vernacular.
- im3w1l 12y agoCausation doesn't imply correlation either, as the causative effect may be cancelled by other effects.
- tel 12y agoYes, there's a lot of caveats in this. Especially around the Co component!
- thanatropism 12y agoAbout linear correlation: there's a Derrida point in statistics where everything becomes relative to a model. Linear correlation is the preferred mode for cardinal (not ordinal) quantities because it's directly related to linear ANOVA (the decomposition of variance between "explained by the covariate" and "unexplained by the covariate") (among many other reasons), but it's a choice. There's nothing outside theoretical decision.