Home Map Help FAQ Trouble

Frequently Asked Questions and Answers

Q. Why can't I see the addresses of crimes?
A. This application is designed to provide crime summaries by select geographies not raw data. Use CLEARMAP Crime Incidents to view individual incident records.

Q. Why can I only search for a 90, 180, 270, or 365-day period?
A. The timeframe choices are limited due to the volume of data and number of crime categories. The four choices provided are sufficient to give the user a sense of the amount of crime recorded by type and location within the City.

Q. Is the crime data back-dated a week like the Crime Incident map?
A. No, because we are not providing specific records. The data is updated daily. The most current information is one day old.

Q. How are the crime count ranges in the Legend determined?
A. The Legend has four ranges denoted by four colors on the map. The ranges are determined using the nested means method. Meaning that for each crime category, timeframe and geography the ranges are calculated dynamically using the current data. This means that the ranges will change over time even when viewing the same geography, crime category and timeframe because the data is dynamic. This means the user should be careful if they try to make comparisons over time.

Q. Are the summary counts official CPD statistics?
A. No, because crime classifications change over time. Due to the dynamic nature of the data the summary counts provided are only intended to provide the user with sense of the data. This site does not replace officially released CPD statistics and information viewed on this site should not be reported as official CPD statistics.

Q. Why do crime classifications change?
A. As additional facts about a case are learned, they can cause the crime classification initially assigned by the preliminary investigator to change. Cases can even be unfounded, which means that further investigation reveals that a crime did not occur at all. (For example, a citizen returns from vacation and finds her lawn mower missing, which she reports to the police. Later, she learns that her son borrowed the lawn mower, and that it was not stolen: no crime occurred.) Due to these changes, long-term comparisons of crime information obtained from this web site will not be reliable.

Q. Does sharing this information jeopardize police operations?
A. In most situations the information shown is based upon reported incidents which have already occurred. Sharing this information will not have an effect on day-to-day police operations. During covert operations, especially involving narcotics, information may not be recorded until the operation has been completed. This will insure the safety of the officers involved as well as prevent suspects from being made aware of confidential activity.

Q. Why do I need to turn off my web browser pop-up blocker?
A. This site uses pop-up windows for several reasons. The primary reason is to maximize the size of the map image by removing unnecessary toolbars, address bars and button bars from the browser window. The Back button on a web browser does not function properly with CLEARMAP and removing it eliminates a potential source of error. Additionally because the application uses framesets it makes printing difficult so, the Print feature opens a map image in a pop-up window. The MapLink feature and the Table printing feature also take advantage of opening new browser windows.

Note: Most modern pop-blockers whether native to the web browser or part of an add-on toolbar like Google or Yahoo allow you to add this website (http://gis.chicagopolice.org) to a list of websites that are allowed to use pop-ups. We recommend taking advantage of this capability to keep your pop-up blocker on while enabling CLEARMAP to function properly.

Q. I have more questions about crime on my beat.
A. Attend your beat meeting and talk to your beat officers! Visit our web site for meeting locations and dates: http://www.cityofchicago.org/police or call Chicago's Non-Emergency telephone number, 3-1-1.

Q. How does the MapLink feature work?
A. The MapLink feature enables people to share a common map view using an encoded URL link. This can be useful for facilitating a discussion about crime in a particular area. When you press the MapLink button a new web page is open with the URL link and a list of the query parameters. The query parameters include the summary geography, crime category and timeframe.  The best way to share this information is to copy the entire page into an email. A quick way to do that on a Windows PC’s is to use Ctrl A (Select All), Ctrl C (Copy), open the email page and press Ctrl V (Paste). Copying the entire page lets your email receiver know where this information came from (gis.chicagopolice.org) and what parameters you had selected when you created the link. Give it a try and remember the receiver needs to be using a supported web browser.