Getting worse all the time, part 3

 In my last post, I observed that the 21st century increase in killings by police seemed to differ by type of place:  according to the Census Bureau's classification, it was considerably larger in small and medium cities and "micropolitan" areas than in "large central metro areas."  In this post, I want to look at this issue another way, using the data from Jason Nix I discussed last time.  One reason is that it's just good to have more sources of data, especially given the limitations of the Vital Statistics data.  Another is that the Census Bureau definition of "large central metro area" is pretty expansive.  For example, it includes Hartford County, Connecticut, which qualifies because it includes the central city of a large metropolitan area, but is mostly suburban (I know this because I lived there for ten years).  The Nix data is at the police department level, so you can get to a finer level of geographical detail.  I went through his data and classified police departments into "big city" and all others.  I didn't have a formal definition, just went by my impression, so there are undoubtedly some questionable decisions (and maybe some outright mistakes).   Still, I think that most people would agree with me on most of them.  

Then I fit two Poisson models with effects for year and place, one for "big cities" and one for other places.  The estimated year effects:

Since I am interested in comparing trends, not absolute rates, the 2000 rate is a baseline for each--below zero means that the rate is lower than it was in 2000, above zero means it's higher.  The rate in big cities  appears to have increased until about 2010 and declined since then; the rate in other places increased more substantially between about 2005 and 2015 and has been steady or declined since then.  In big cities, the latest (2022) rate is the same or a little lower than the 2000 rate; in other places, it's clearly higher.  

But the standard errors are pretty large, especially for other places, so I fit another model, with year effects plus a time trend/city size interaction.  That is, it says that there are short-term ups and downs that apply to both types of places, but also a gradual drift that differs between the two types.  The estimates:

Overall, the evidence is that the rate of killings by police in large cities has declined in the last decade or so, but the rate in smaller places has stayed the same or increased.  Why?  In a general sense, I think that it's because the rise in public concern with the issue has had more impact in larger cities.  Killings by police are more likely to happen in larger places (if only because the population is larger), and to get more media coverage (since newspapers and TV stations are located there), so the pressure to keep the numbers down is stronger.  How they actually accomplished it probably involves specific practices and training, and I don't know anything about policing, so I don't have any ideas.

The Lancet article that started me on these posts says:  "more recent reform efforts to prevent police violence in the USA, including body cameras, implicit bias training, de-escalation, and diversifying police forces, have all failed to further meaningfully reduce police violence rates.  As our analysis shows, fatal police violence rates and the large racial disparities in fatal police violence have remained largely unchanged or have increased since 1990."  There analysis actually showed that racial disparities had declined, but even apart from that, stability or increase in the overall rates doesn't mean that reforms have been ineffective:  it's possible that there are some factors that have worked to increase rates and others that have reduced them.  The fact that the rates have moved in different directions in different places suggests that is the case.  

PS:  On the same general subject, Peter Moskos has compiled data on fatal police shootings in 18 cities in the 1970s and the present.  It declined in 14, stayed about the same in three, and increased in two.