About the data
The data the CBS News Chicago Gun Violence Tracker comes from the Chicago Police Department's Violence Reduction dataset and the Cook County Medical Examiner Case Archive data. Both data sets are updated daily, and this tracker pulls the data around 8:00 am Central Time.
The Chicago Violence Reduction data typically has a lag of about two days (meaning, data updated today will be current through two days ago) but can sometimes stretch longer. According to CPD, "each time the dataset is refreshed, records can change as CPD learns more about each victimization, especially those victimizations that are most recent...some recorded data about incidents and victimizations may change once additional information arises. Regularly updated datasets on the City's public portal may change to reflect new or corrected information."
The Cook County Medical Examiner data contains information only about deaths that occurred in Cook County that were under the Medical Examiner’s jurisdiction, which does not include all deaths that occur in Cook County. For this tracker, that data is then filtered by deaths that are "gun related." Even though the data is updated daily and typically has some data from the same day, information on gun-related deaths can lag a bit longer.
There are two dates in the Cook County Medical Examiner data: incident date and death date. For the purposes of this tracker, the main date we used is the incident date. If that isn't available then the death date is used. The data reflects numbers through the most recent date that the Medical Examiner reported a gun-related death, which can often be earlier than the most recent of all deaths reported.
Designed and built by Elliott Ramos and Grace Manthey
