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What seems to be missing to me is any support for the "random sampling" claim. My starting assumption is that reports on police shootings would be full of syst
by Bartweiss 10y ago
What seems to be missing to me is any support for the "random sampling" claim. My starting assumption is that reports on police shootings would be full of systematic biases running in all sorts of directions.
Without some actual argument that this data isn't horribly biased by exactly the issues it's trying to investigate, I'm not sure what worth to give it.
- minimaxir 10y agoSpecifically, random sampling assumes that data points are independent and identically distributed: https://en.wikipedia.org/wiki/Independent_and_identically_distributed_random_variables https://en.wikipedia.org/wiki/Independent_and_identically_di... As others have pointed out, that is not a great assumption in this case.
- apathy 10y agoIt isnt, and indeed it is rarely satisfied. The real question is how sensitive the resulting model may be to violations of this assumption. Greg Ridgway looked at a natural experiment (proportion of drivers pulled over 1 hour before dawn, when the color of the driver is very hard to determine a priori, vs that proportion 1 hour after dawn, where it is easy) back when he was at RAND, and came to a similar conclusion. Ymmv. Obviously, "pulled over" is not the same as "shot" but the objective data is easier to come by. Especially if you don't tell the LAPD what specifically you're studying beforehand.