Data are provided to the National Juvenile Court Data Archive by State and local agencies responsible for the collection and/or dissemination of juvenile justice data. The information contributed by these agencies is not derived from a probability sampling procedure, nor is it the result of a uniform data collection effort. The national estimates described in this Bulletin and in Juvenile Court Statistics are developed using information from all courts able to provide compatible data to the Archive. While juvenile courts with jurisdiction over 96% of the U.S. juvenile population contributed at least some 1996 data to the Archive, not all information could be used to generate the national estimates because of incompatibilities in the structure or content of the data files.

Data are provided to the Archive in two forms—automated case-level data and court-level aggregate data. Automated case-level data for 1996, which describe each case's demographic and processing characteristics, were provided by 1,317 jurisdictions in 26 States (Alabama, Arizona, Arkansas, California, Connecticut, Florida, Illinois, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New York, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Utah, Virginia, Washington, and West Virginia). Together, the contributing jurisdictions from these States contained 52% of the Nation's juvenile population (i.e., youth ages 10 through the upper age of original juvenile court jurisdiction in each State). Compatible court-level aggregate data for 1996, which usually indicate the number of delinquency cases disposed in a calendar year, were provided by an additional 516 jurisdictions in 8 States (California, Hawaii, Idaho, Illinois, Indiana, New York, Texas, and Vermont) and the District of Columbia. In all, compatible 1996 data were provided to the Archive by 1,775 jurisdictions, containing 67% of the Nation's juvenile population.

The national estimates of juvenile court cases reported in this Bulletin and in Juvenile Court Statistics were developed using the Archive's case-level and court-level data files combined with county-level juvenile population estimates (controlling for the upper age of original juvenile court jurisdiction in each State). The basic assumption underlying the estimation procedure is that the volume and characteristics of juvenile court cases are shaped by the same set of factors in reporting and nonreporting jurisdictions of similar size. For interested readers, a complete description of the estimation procedure appears in the "Methods" section of each Juvenile Court Statistics Report.