add police killings data

police-killings/README.md

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+### Police Killings
+
+This directory contains the data behind the story [Where Police Have Killed Americans In 2015](http://fivethirtyeight.com/features/where-police-have-killed-americans-in-2015).
+
+We linked entries from the [Guardian's database on police killings](http://www.theguardian.com/us-news/ng-interactive/2015/jun/01/the-counted-map-us-police-killings) to census data from the American Community Survey. The Guardian data was downloaded on June 2, 2015. More information about their database is available [here](http://www.theguardian.com/us-news/ng-interactive/2015/jun/01/about-the-counted).
+
+Census data was calculated at the tract level from the 2015 5-year American Community Survey using the tables `S0601 (demographics)`, `S1901 (tract-level income and poverty)`, `S1701 (employment and education)` and `DP03 (county-level income)`. Census tracts were determined by geocoding addresses to latitude/longitude using the Bing Maps and Google Maps APIs, then overlaying points onto 2014 Census tracts. GEOIDs are Census-standard and should be easily joinable to other ACS tables -- let us know if you find anything interesting.
+
+Field descriptions:
+
+Header | Description | Source
+---|-----------|----
+`name` | Name of deceased | Guardian
+`age` | Age of deceased | Guardian
+`gender` | Gender of deceased | Guardian
+`raceethnicity` | Race/ethnicity of deceased | Guardian
+`month` | Month of killing | Guardian
+`day` | Day of incident | Guardian
+`year` | Year of incident | Guardian
+`streetaddress` | Address/intersection where incident occurred | Guardian
+`city` | City where incident occurred | Guardian
+`state` | State where incident occurred | Guardian
+`latitude` | Latitude, geocoded from address | 
+`longitude` | Longitude, geocoded from address | 
+`state_fp` | State FIPS code | Census
+`county_fp` | County FIPS code | Census
+`tract_ce` | Tract ID code | Census
+`geo_id` | Combined tract ID code | 
+`county_id` | Combined county ID code | 
+`namelsad` | Tract description | Census
+`lawenforcementagency` | Agency involved in incident | Guardian
+`cause` | Cause of death | Guardian
+`armed` | How/whether deceased was armed | Guardian
+`pop` | Tract population | Census
+`share_white` | Share of pop that is non-Hispanic white | Census
+`share_bloack` | Share of pop that is black (alone, not in combination) | Census
+`share_hispanic` | Share of pop that is Hispanic/Latino (any race) | Census
+`p_income` | Tract-level median personal income | Census
+`h_income` | Tract-level median household income | Census
+`county_income` | County-level median household income | Census
+`comp_income` | `h_income` / `county_income` | Calculated from Census 
+`county_bucket` | Household income, quintile within county | Calculated from Census
+`nat_bucket` | Household income, quintil nationally | Calculated from Census
+`pov` | Tract-level poverty rate (official) | Census
+`urate` | Tract-level unemployment rate | Calculated from Census
+`college` | Share of 25+ pop with BA or higher | Calculated from Census
+
+<b>Note regarding income calculations:</b>
+
+All income fields are in inflation-adjusted 2013 dollars.
+
+`comp_income` is simply tract-level median household income as a share of county-level median household income.
+
+`county_bucket` provides where the tract's median household income falls in the distribution (by quintile) of all tracts in the county. (1 indicates a tract falls in the poorest 20% of tracts within the county.) Distribution is not weighted by population.
+
+`nat_bucket` is the same but for all U.S. counties.