Another Layer to Mapping Police Violence

A FiveThirtyEight dot com recently released a podcast episode with the founder of Mapping Police Violence (check it out here). Mapping Police Violence (MPV) looks across multiple sources in an attempt to collect all incidents of police involved killings in the US.

Below is a heat map of all the zip codes with police violence with a scale from white to blue indicating the number of lives lost.

In an attempt at to examine the underlying communities affected, I paired MPV data with American Community Survey (ACS) demographic data at the zip code level to see any key features of areas affected by theses incidents. MPV data included over 4k incidents from 2013-2016. ACS includes over 32k zip codes with demographics including population, ethnicities, income, rent and age. Below are eight density plots comparing zip codes affected by a police shooting ("1") to the entire population ("0").

The most noticeable features are the population, the percent white, and median age. Areas effected are more densely populated, and have a lower white population and a lower average age. One surprising finding is how the median rent is higher in the incident zip codes. Most likely, this is a result of the the high occurence in dense urban areas which have higher rents than less populated zip codes. In order to add an additional layer, I decided to look at the number of killings within in each zip code in the past three years, from 0-4. I paired these with demographics and the findings were more telling.

The most glaring result is how areas with 3-4 killings (purple and blue shading) in the past three years had a very low white population and much higher percent black and hispanic. In fact with each additional violent incident the mean white population is lower by an additional 10 to 15%. Contrarily, the population of each zip code on average increases by 5k to 10k with each additional incident. Below are the summary statistics for each grouping.

I will continue exploring these dataset and hopefully adding more layers as I find them. I hope these summaries add some insight to a complicated matter.

Sources:

Demographic Data - 2012 American Community Survey

Police Violence Incidents Data - Mappingpoliceviolence.org

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Visualizations by Spencer Davison and inspired by d3js.org, Tableau Public, bl.ocks.org and various other sites in the analytics community.