Measuring police bias using simple ratios doesn't work. You can never cleanly separate the impact of race from other factors associated with race.
Instead, I want augmented-reality goggles that make race invisible. Then we could run the following experiment:
- Have half of police wear race-invisibility goggles for a year.
- Have the other half wear non-invisibility goggles.
- Look at the difference of the two groups.
The police with invisibility goggles would not have equal statistics with respect to race, because race is correlated with many things other than how people appear. However, since the only difference between the two groups is if police can see race, the difference reveals exactly the impact of police bias.
We can't do this experiment, but we can do kind of low-tech approximation. Instead of augmented reality goggles we use the geometry of the earth and sun. [continues here]