TycheDataGuide:CrimeData

Crime Data Example from Denver, CO

What is Crime Data?

Crime data can take many forms - incident-by-incident data, crime data aggregated at a neighborhood level, crime trends, crime categorization and more. Crime data typically consists of individual incident data, and for each incident:

• when did it happen
• what crime or crimes were the outcome OR was the disposition that no crime was assessed
• a crime category
• location information
• demographic information on the alleged purpetrators and/or victimes

For public data analysis and data storytelling we recommend acquiring incident level data. Crime incident data will list out a crime (or incident), the time when it happened, the nature of the crime or incident, and other details.

Of importance when acquiring incident level data is to determine if the data represents crime (a person was arrested, charged, given an appearance ticket, given a citation) or if the data represents a police action which could include a crime or the investigation into an issue which could involve remediating the issue on arrival or determining that no crime can be found or identified.

Where does it come from?

Crime data is almost always collected and managed by the local law enforcement department, be it a public safety, sheriff or police department. Multiple law enforcement departments may cover a single area, for example a city may utilize policing from the city, county and state. When exploring an area's crime statistics you would want to determine which law enforcement agencies are collecting and distributing data on crimes.

How do you acquire Crime Data?

Crime data is not as regularly found on open data sites at the incident level. You are more likely to find crime summaries (e.g. crime by neighborhood) and crime maps.

Crime data can require FOIL or open data requests. One would typically file a public informaiton request by asking for:

"All individual or incident-specific crime data between <some time period> with date and time, incident codes which will include FBI UCR coding if found, and any location information such as address or neighborhood"

What are the primary and secondary data elements?

Crime or incident level data will contain attributes such as:

1. a unique ID for each incident, typically a proprietary or law enforcement-specific identifer
2. date and time
3. address or general location (X00 block, street intersection, neighborhood) which could also include information such as the type of location (a parking lot, a retail location, outside on a sidewalk)
4. categorization and crime definition using FBI Uniform Crime Reporting definitions
5. a local definition for the categorization of the crime or incident
6. officer response information

What are questions that you can answer with Crime Data?

Questions that you can answer using crime data fall into several categories - trends, incident types, response. Some of the many questions you can answer with crime data include:

1. Is crime rising, falling or staying constant?
2. Where is crime primarily happening in the area and which areas would be considered safer?
3. What is the seasonality and day-to-day variability of crime?
4. What crimes make up the overall pie, and how much?
5. Is it possible to understand how changes in policing are impacting crime count and type?
6. What percentage of criminal stops end with no outcome or action?

All questions above can be aggregated to subgeographies such as neighborhoods, census tracts, local incorporated or unincorporated entities and more

Tips and tricks for using Crime Data?

1. Identify if the crime data comes with FBI Uniform Crime Reporting definitions or if the local crime data has its own proprietary defenitions or categories. Sometimes local crime data has both - a field for the UCR crime category and a local crime category.
2. Crime data may come with location coordinates (x & y, latitude and longitude), specific addresses (e.g. "10 Main St") or partially anonymized addresses (e.g. "300 Block of 3rd St").
3. Crime data can be influenced by many external factors. These factors may influence the volume and types of crimes that are found in the data. External factors can include:
   • law enforcement leadership in collecting crime statistics
   • the technologies available for capturing timely crime statistics
   • the number of law enforcement officers who are in policing positions