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Really interesting. Biggest complaint is the author takes a long time to explain the thermostat model. Here is the definition: Everybody knows that if you pr
by kevin_morrill 14y ago
Really interesting. Biggest complaint is the author takes a long time to explain the thermostat model. Here is the definition:
Everybody knows that if you press down on the gas pedal the car goes faster, other things equal, right? And everybody knows that if a car is going uphill the car goes slower, other things equal, right?
But suppose you were someone who didn't know those two things. And you were a passenger in a car watching the driver trying to keep a constant speed on a hilly road. You would see the gas pedal going up and down. You would see the car going downhill and uphill. But if the driver were skilled, and the car powerful enough, you would see the speed stay constant.
So, if you were simply looking at this particular "data generating process", you could easily conclude: "Look! The position of the gas pedal has no effect on the speed!"; and "Look! Whether the car is going uphill or downhill has no effect on the speed!"; and "All you guys who think that gas pedals and hills affect speed are wrong!"
- 1337biz 14y agoI'm really looking forward to the comments on this one. Overall it is a variation on the "correlation is not causation" theme and that defining variables in a social setting is super tricky, if not to say impossible.
- cousin_it 14y agoIt seems to me that when people say "correlation is not causation", they typically mean you can't learn about a causal relationship by just looking at the correlation. The article makes the converse statement: you can't infer the absence of a causal relationship from the absence of correlation, or equivalently (contrapositive), even when you know there is a causal relationship, it won't necessarily lead to a visible correlation in the data.
- endersshadow 14y agoWell, more to the point: The data analysis game changes entirely once you've introduced an intelligent actor (in this case the driver).
- cousin_it 14y agoFeedback processes don't have to be intelligent, e.g. the thermostat mentioned in the title.
- Symmetry 14y agoIt's actually much more subtle than "correlation is not causation". More like "goal seeking behavior can remove all correlation from a causal relationship," which is very different since causation normally causes correlation, and normally is you don't see correlation you can be sure that there isn't any causation.