Some nerd notes on algae (inspired by the recent algae in the reflecting pool notes I see in the timeline). The algae that sit at the top of the water (cyanobacteria) are bad for multiple reasons. They tend to kill other flora and fauna in the water sources, and emit greenhouse gases. It is a problem in natural water sources as well, in particular ones around farming areas that have sources of nitrogen. So I do not know the filtration with the reflecting pool, but there are non-chemical solutions. One solution is to use ultrasonic frequency to kill the algae. There are commercial products available now for this. The other I am familiar with (which makes more sense for natural areas) are to basically seed the pool with good bacteria (diatoms) that sink and do not cause the toxic blooms. They compete and eat up the food, so the bad bacteria cannot take root.

Journey to crime flow data is hard to visualize.

Example of clustering flows.

We know that not all crimes are reported, so I presented one way to adjust reported crime estimates given this undercounting. If you have a crime reporting rate of 50%, and you observe 100 crimes, the up-adjusted number of crimes is 200. In a paper with Alex Piquero, I extend this to show up-adjusted estimates of serious domestic violence combining NIBRS and NCVS.

The biggest critique of this work is it begs the question of whether the NCVS estimate can be applied to micro places based on demographics. E.g. can the nationwide sample approximate the reporting rate for any city (or even smaller neighborhood). I think that is likely yes, but it is an empirical question.