One of the key technical features of the ILDS is the Centralized Demographic Dataset (CDD).
The CDD provides technical review procedures and software to securely and confidentially match data records across the partner agency systems. For example, state agencies use different identifiers for the same individual. As a result, a person may have one identifier in an Illinois Department of Human Services (IDHS) early childhood system, which is different than the identifier for her in the Illinois State Board of Education (ISBE) K-12 system, and also different for her in the Illinois Department of Employment Security (IDES) employment records system. The CDD matches the data across systems using multiple identifiers of each person to create a secured index for the data that protects the privacy and safety of Illinois' students and families.
Records matched by the CDD can be provided back to state agencies for ILDS-related projects. The ILDS can never be used to view individual outcomes; it can only be used to analyze aggregate information involving multiple individuals in ways that ensure that anyone reviewing the information cannot identify any specific individuals.
Known as the CDDA, a team at Northern Illinois University’s
Center for Governmental Studies administers and maintains the CDD. More
information on the CDDA team and its linkage methodology is available here.