Data Sources


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Data Sources

Arrest data

The Illinois Criminal Justice Information Authority's Criminal History Record Information (CHRI) Ad Hoc datasets are the source of arrest data presented here. These data are derived from records in the Illinois State Police's (ISP) Computerized Criminal History (CCH) system, the state's central repository for criminal history record information. Fingerprint-based arrest cards used by law enforcement are entered into the state system. The Authority, in cooperation with ISP, has established an in-house computer linkage that allows us to derive arrest statistics and demographic characteristics from the individual records.

The CCH system is a live database and its data are updated and changed constantly by ISP, leading to potential changes in statistical information derived from it. Data are based on the number of arrest incidents, not the number of unique individuals arrested. Law enforcement is only required to report felony arrests for juveniles. Misdemeanor offenses may be submitted, but are not mandatory.

Detention data

Data from juvenile temporary detention centers were extracted from the Illinois Juvenile Monitoring Information System (JMIS) database. JMIS is a web-based management information system, managed by the University of Illinois that allows Illinois juvenile detention centers to electronically submit data.

Detention admissions include juveniles that are admitted pre-adjudication and post-adjudication. It is not possible to distinguish between these two groups. Decisions to detain juveniles prior to adjudication are made using a scorable detention screening instrument. While the decision to detain is determined by their score on the screening tool, youth can be detained pre-adjudication if the screener feels the youth should not be returned to their home environment for safety or other reasons.

The offenses for which youth are detained are grouped into eight categories: property, person, drug, sex, "other," noncompliance, status offenses, and youth detained for a warrant. Offenses designated as "other" include such offenses as disorderly conduct, mob action, and traffic violations. Further explanation of offense categories is provided later.

Corrections data

Data from the Juvenile Division of the Illinois Department of Corrections (IDOC), now known as the Illinois Department of Juvenile Justice (IDJJ), were only available up to state fiscal year 2004. The Authority used its own method of categorizing offenses, discussed later, so data may differ slightly from official IDOC statistical reports.

New sentence commitments to IDOC were examined separately from admissions for technical violations of a youth's parole or mandatory supervised release. IDOC commitments discussed in this report include juveniles committed to an IDOC facility only for new sentences, unless otherwise specified.


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