That would take a lot of work, and would be problematic even if I put in the time, since with any given implementation, we could point out other factors. Besides, we'd be working with a very long time scale. How long, for example, has NY had policies favoring dense building and mass transit? But, what we can do is compare liberal areas, as a group, to conservative areas, as a group, and see what the outcomes look like. If one set of areas is having desirable results, on average, and the other is having undesirable results, we'd be wiser to experiment with the solutions favored by the group experiencing success.