About: St. Louis city
These notes explain caveats and methodology specific to the St. Louis city section of our Crime Tracker. For general notes about the entire app, go to the main About page.
St. Louis city data
The St. Louis city crime tracker is built using data from the St. Louis Police Department's crime report CSVs. These reports are posted monthly, and each CSV lists all incidents (or "complaints") in a given month.
Per-capita crime rates
Per-capita crime rates are based on neighborhood populations, which come with some important caveats:
- The population totals we use to calculate per-capita crime rates are derived from the 2010 Census. Obviously, these rates do not factor in changes that have occurred since 2010.
- Daytime and nighttime populations of neighborhoods can be significantly higher than the residential population, which can skew crime rates upward. For example, the Downtown and Downtown West neighborhoods regularly have some of the highest per-capita crime rates in the city, mostly due to the large influx of people who don't live in the area.
- We do not display per-capita crime rates for parks or for neighborhoods with populations of less than 300 residents.
- For most incidents, police crime reports include X- and Y- coordinates for an incident. We convert the police-provided coordinates into latitude and longitude to generate markers for those incidents.
- For some incidents, police omit coordinates but still provide an address or an intersection. In these cases we generate markers by submitting the address to a geocoding service.
- Police sometimes mark an incident as taking place in a particular neighborhood, but the coordinates and/or the address they provide place the incident within an adjacent neighborhood's boundaries. We are aware of this discrepancy, but do not attempt to correct it on the map.
- Markers for rapes on our incident maps are only approximations. In cases of rape, police reports round off addresses in order to avoid identifying victims. For example, "the 2300 block of Fake Street" instead of "2356 Fake Street."
- Incidents which lack coordinates or addresses in the police report have been omitted from the map.
- Each neighborhood's report page includes a "total crime by month" chart and two "year-over-year change" charts.
- We fix the scale of these charts so that they are the same on every neighborhood report page in St. Louis city. Doing this allows readers to compare the charts visually from page to page. This design choice also helps avoid exaggerating small numbers in places with little crime.