Where does the data come from?

• Each morning by 7:30 AM, the Tucson Police Department makes available for download a file containing records of police incidents for the most recent 45 days. The records are extracted from the Department's Records Management System, geocoded to Pima County street centerlines with a 30 foot offset to obtain X and Y coordinates for the location of the incident and packaged for download. The data file typically includes information about incidents that were reported as recently as 11:59 PM from the day before.

How is the neighborhood label established for each incident?

• Each morning just after 7:30 AM, NSN downloads the police incident file. The file is processed for addition to a PostgreSQL database table. A PostGIS-enabled query matches the police incident data points with a file of neighborhood polygons that is based on the City of Tucson Housing and Community Development Department's neighborhood boundary file (nha_city.shp). Additional neighborhoods, not registered with HCD, have been added to the base file. Incidents along boundary streets, particularly at intersections, may or may not be assigned to a given neighborhood. Finalized web pages are uploaded to the NSN website, usually by 8:30 AM.

How reliable is the data?

• Police incident data used here covers the City of Tucson. It does not include data from Pima County, South Tucson, University of Arizona, Pima Community College, Davis Monthan AFB, Tucson International Airport, state, federal or other law enforcement agencies.
  
  Police incidents were screened according to definitions included in the local version of the Uniform Crime Reporting program of the U.S. Federal Bureau of Investigation. Police incident information is approximate and subject to change. This is particularly true of the most recent information.
  
  Data on reported and discovered police incidents is based on factors that change over time; therefore use of this data should be made with caution. Some factors affecting police data are:
  • Actual numbers of police incidents as interpreted through Uniform Crime Reporting rules, including record updates based on new information
  • Rate of reporting by citizens or crime victims
  • Time lags in completion of or automation of police reports
  • Neighborhood boundaries as included in geoprocessing tables
  • Special efforts of police to reduce crime (which may increase the amount of crime known to police)
  • Special efforts of victims to reduce crime, such as shoplifting prevention programs (which may increase the amount of crime known to police)
  • Data processing practices, including geocoding match rate (approximately 99.3% for this data)
  • Changes in the law or in criminal justice system policies and practices

Did the updating work this morning?

• Some listings will not show any incidents from yesterday, making the viewer wonder whether the current file was updated this morning. No incidents may come from the fact that there were no police incidents in the neighborhood during the last 24 hours. Check other neighborhoods.
  
  Another reason may be that the update process did not work correctly. The program is set to send an administrative email message to the database manager when errors occur. It is also possible that a computer was down when the timed update process was to occur or that no fresh data was available. Here is a page that will describe the latest data file available from TPD.

How can I contact you?

• This system was created by Donald Ijams, who can be reached at dsijams -at- gmail.com . Feedback and error correction information is most welcome.

Tell me about the columns on the listing.

• Location of Incident

  • This is the street address where the incident occurred. The street number is masked to protect victims from harassment. This address is approximate as many incidents will have happened in the street in front of the house, or in the alley or in the parking lot. The incident may have nothing to do with the occupants of the nearest building.
  
  

• Date Reported

  • The date the incident was reported to or discovered by Tucson Police is shown here. This may not be the date the incident happened.
  
  

• Time Reported

  • The time the incident was entered into the Tucson Police computer assisted dispatch system or main database is shown here. This is not the time the incident occurred.
  
  

• Incident Dispatched As

  • Most often, as a result of the reporting party's telephone conversation with Tucson Police, the police service operator will enter a code that tells the dispatched officer what to expect. This information is only preliminary and does not reflect what the officer found.
  
  

• Officer Cleared Incident As

  • After Tucson Police personnel complete their preliminary investigation at the scene, the primary officer will enter a computer code showing what was found. This code may be altered after follow up investigation occurs or after review by police records personnel.
  
  

• Case Number

  • Each police incident receives a ten digit case number, to uniquely identify it in the records system. Use this number to refer to a specific case.
  
  

• Inv

  • Almost all cases cleared as a crime are sent to a TPD investigative unit for review and possible followup investigation. The codes shown in the listing tell where the case was routed. Not all reported crimes will be investigated beyond the officer's preliminary investigation. The investigative sergeant will look for leads that can be used to solve the case and will have to decide where to allocate scarce detective time. Recent cases may not be routed or reviewed for several days.