line Methods

Juvenile Court Statistics (JCS) utilizes data provided to the National Juvenile Court Data Archive by State and county agencies responsible for collecting and/or disseminating information on the processing of youth in juvenile courts. These data are not the result of a uniform data collection effort. They are not derived from a complete census of juvenile courts or obtained from a probability sample of courts. The national estimates presented in this report are developed using compatible information from all courts that are able to provide data to the Archive.

Sources of Data
The Archive collects data in two forms: court-level aggregate statistics and detailed case-level data. Court-level aggregate statistics are either abstracted from the annual reports of State and local courts or are contributed directly to the Archive. Court-level statistics typically provide counts of the delinquency and status offense cases handled by courts in a defined time period (calendar or fiscal year).

Case-level data are usually generated by the automated client-tracking systems or case-reporting systems managed by juvenile courts or other juvenile justice agencies. These systems provide detailed data on the characteristics of each delinquency and status offense case handled by courts, generally including the age, sex, and race of the youth referred; the date and source of referral; the offenses charged; detention; petitioning; and the date and type of disposition.

The structure of each data set contributed to the Archive is unique, having been designed to meet the information needs of a particular jurisdiction. Archive staff study the structure and content of each data set in order to design an automated restructuring procedure that will transform each jurisdiction’s data into a common case-level format.

The aggregation of these standardized case-level data files constitutes the Archive’s national case-level data base. The compiled data from jurisdictions that contribute only court-level statistics constitutes the national court-level data base. Together, these two multijurisdictional data bases are used to generate the Archive’s national estimates of delinquency and status offense cases.

Each year, juvenile courts with jurisdiction over more than 95% of the U.S. juvenile population contribute either case-level data or court-level aggregate statistics to the Archive. However, not all of this information can be used to generate the national estimates contained in JCS. To be used in the development of national estimates, the data must be in a compatible unit of count (i.e., case disposed), the data source must demonstrate a pattern of consistent reporting over time (at least 2 years), and the data file contributed to the Archive must represent a complete count of delinquency and/or status offense cases disposed in a jurisdiction during a given year.

In 1995, case-level data describing 876,173 delinquency cases handled by 1,323 jurisdictions in 28 States met the Archive’s criteria for inclusion in the development of national estimates. Compatible data were available from Alabama, Arizona, Arkansas, California, Connecticut, Florida, Hawaii, Illinois, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New York, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, and West Virginia. These courts had jurisdiction over 53% of the Nation’s juvenile population in 1995. Compatible court-level aggregate statistics on an additional 176,823 delinquency cases from 511 jurisdictions were reported from the District of Columbia and the States of California, Idaho, Illinois, Indiana, Montana, Texas, and Vermont. In all, the Archive received compatible case-level data and court-level statistics on delinquency cases from 1,775 jurisdictions containing 67% of the Nation’s juvenile population in 1995 (table A-1).

Case-level data describing 74,393 formally-handled status offense cases from 1,398 jurisdictions in 28 States met the estimation criteria for 1995. The contributing States were Alabama, Arizona, Arkansas, California, Connecticut, Florida, Hawaii, Illinois, Iowa, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New York, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, and West Virginia. These courts had jurisdiction over 52% of the juvenile population. An additional 412 jurisdictions in 4 States (California, Idaho, Indiana, and Texas) and the District of Columbia reported compatible court-level aggregate statistics on 9,357 petitioned status offense cases. Altogether, compatible case-level and court-level data on petitioned status offense cases were available from 1,810 jurisdictions containing 63% of the U.S. juvenile population (table A-2).

Table A-1: 1995 Stratum Profiles: Delinquency Data

Table A-2: 1995 Stratum Profiles: Status Offense Data

Youth Population at Risk
The volume andcharacteristics of juvenile court caseloads are partly a function of the size and demographic composition of a jurisdiction’s population. Therefore, a critical element in the Archive’s development of national estimates is the population of youth that generate the juvenile court referrals in each jurisdiction -- i.e., the "youth at risk" or "juvenile" population of every U.S. county.

A survey of the Archive’s case-level data shows that very few delinquency or status offense cases involve youth younger than 10. Therefore, the lower age limit of the youth population at risk is set at 10 years for all jurisdictions. On the other hand, the upper age limit varies by State. Every State defines an upper age limit for youth who will come under the jurisdiction of the juvenile court if they commit an illegal act. (See "upper age of jurisdiction" in the "Glossary of Terms" section.) Most States define this age to be 17 years, although some States have set the age at 15 or 16. States often enact exceptions to this simple age criterion (e.g., youthful offender legislation, concurrent jurisdiction or extended jurisdiction provisions). In general, however, juvenile courts have responsibility for all law violations committed by youth at or below the upper age of original jurisdiction.

For the purposes of this Report, therefore, the youth population at risk is defined as the number of youth living in a jurisdiction who are at least 10 years old but who are not older than the upper age of original juvenile court jurisdiction. For example, in New York, where the upper age of juvenile court jurisdiction is 15, the youth population at risk is the number of youth residing in a county who are between the ages of 10 and 15.

The youth-population-at-risk estimates used in this Report were developed with data from the Bureau of the Census.1 The estimates, separated into single-year age groups, contain the number of whites, blacks, and individuals of other races who reside in each county in the Nation and who are between the ages of 10 and the upper age of original juvenile court jurisdiction.2

Estimation Procedure
National estimates are developed using the national case-level data base, the national court-level data base, and the Archive’s youth-population-at-risk estimates for every U.S. county. "County" was selected as the unit of aggregation because (1) most juvenile court jurisdictions in the United States are concurrent with county boundaries, (2) most data contributed by juvenile courts include the county in which the case was handled, and (3) youth population estimates can be developed at the county level.3

The Archive’s national estimates are generated by analyzing the data obtained from its nonprobability sample of juvenile courts and then weighting (multiplying) those cases to represent the number of cases handled by juvenile courts nationwide. The Archive employs an elaborate multivariate weighting procedure that adjusts for a number of factors related to juvenile court caseloads -- i.e., the court’s jurisdictional responsibilities (upper age); the size and demographic composition of the community; the age, sex, and race profile of the youth involved in juvenile court cases; and the offenses charged against the youth.

The basic assumption underlying the estimation procedure is that similar legal and demographic factors shape the volume and characteristics of cases inreporting and nonreporting counties of comparable size and features. The estimation procedure develops independent estimates for the number of petitioned delinquency cases, the number of nonpetitioned delinquency cases, and the number of petitioned status offense cases handled by juvenile courts nationwide. Identical procedures are used to develop all case estimates.

The first step in the estimation procedure is to place all U.S. counties into one of four strata based on the population of youth between the ages of 10 and 17. The lower and upper population limits of the four strata are defined each year so that each stratum contains one-quarter of the national population of youth between the ages of 10 and 17. In each of the four strata, the Archive determines the number of at-risk youth in three age groups: 10- through 15-year-olds, 16-year-olds, and 17-year-olds. The three age groups are further subdivided into three racial groups -- white, black, and other. Thus, youth-at-risk population estimates are developed for nine age-by-race categories in each stratum of counties.

The next step is to identify the jurisdictions within each stratum that contributed case-level data to the Archive consistent with JCS reporting requirements. The national case-level data base is summarized to determine the number of court cases within each stratum that involved youth in each of the nine age/race population groups. Case rates (number of cases per 1,000 youth at risk) are developed for the nine age/race groups within each of the four strata.

For example, assume that a total of 3,339,000 white youth between the ages of 10 and 15 resided in the stratum 4 counties that reported case-level data to the Archive. If the Archive’s case-level data base shows that the juvenile courts in these counties handled 56,575 petitioned delinquency cases involving white youth between the ages of 10 and 15, the number of cases per 1,000 white youth ages 10 to 15 for stratum 4 would be 16.9, or:

(56,575/3,339,000) x 1,000 = 16.9

Comparable analyses are then used to establish the stratum 4 case rate for black youth between the ages of 10 and 15, and the case rate of 10- through 15-year-olds of other races per 1,000 youth at risk in the population (51.2 and 8.7, respectively).

Next, information contained in the national court-level data base is introduced, and case rates are adjusted accordingly. First, each court-level statistic is disaggregated into the nine age/race groups. This separation is accomplished by assuming that for each jurisdiction, the relationships among the stratum’s nine age/race case rates (developed using the case-level data) are paralleled in the aggregate statistic.

For example, assume that a jurisdiction in stratum 4 with an upper age of 15 processed 600 cases during the year and that this jurisdiction had a population-at-risk of 12,000 white youth, 6,000 black youth, and 2,000 youth of other races. The stratum 4 case rates for white, black, and other race youth between the ages of 10 and 15 would be multiplied by the corresponding populatio to develop estimates of the proportion of the court’s caseload that came from each age/race group.

The jurisdiction’s total caseload of 600 would then be allocated based on these proportions. In this example, 38.5% of all cases reported in the jurisdiction’s aggregate statistics involved white youth, 58.2% involved black youth, and the remaining 3.3% involved youth of other races. When these proportions are applied to a reported aggregate statistic of 600 cases, this jurisdiction is estimated to have handled 231 white youth, 349 black youth, and 20 youth of other races age 15 or younger. The same method is used to develop case counts for all nine age/race groups for each jurisdiction reporting only aggregate court-level statistics.

The disaggregated court-level counts are added to the counts developed from case-level data to produce an estimate of the number of cases involving each of the nine age/race groups handled by reporting courts in each of the four strata. The population-at-risk figures for the entire sample are also compiled. Together, the case counts and the population-at-risk figures are used to generate a revised set of case rates for each of the nine age/race groups within the four strata.

Stratum estimates for the total number of cases involving each age/race group are then calculated by multiplying the revised case rate for each of the nine age/race groups in a stratum by the corresponding youth population at risk in all counties belonging to that stratum (both reporting and nonreporting).

After the national estimate for the total number of cases in each age/race group in each stratum has been calculated, the next step is to generate estimates of their case characteristics. This estimate is accomplished by weighting the individual case-level records stored in the Archive’s national case-level data base. For example, assume that the Archive generates an estimate of 32,100 petitioned delinquency cases involving white 16-year-olds from stratum 4 juvenile courts. Assume also that the national case-level data base for that year contained 25,454 petitioned delinquency cases involving white 16-year-olds from stratum 4 counties. In the Archive’s national estimation data base, each stratum 4 petitioned delinquency case that involved a white 16-year-old would be weighted by 1.26, because:

32,100/25,454 = 1.26

The final step in the estimation procedure is to impute missing data on individual case records. Table A-3 indicates the standardized data elements that were available from each jurisdiction’s 1995 data set. The procedures to adjust for missing data assume that case records with missing data are similar in structure to those without missing data. For example, assume that among cases from a particular stratum, detention information was missing on 100 cases involving 16-year-old white males who were petitioned to court, adjudicated for a property offense, and then placed on probation. If similar cases from the same stratum showed that 20% of these cases involved detention, then it would be assumed that 20% of the 100 cases missing detention information also involved detention. Thus, missing data are imputed within each stratum by reviewing the characteristics of cases with similar case attributes (i.e., the age, sex, and race of the youth; the offense charged; and the court’s decisions on detention, petition, adjudication, and disposition).

More detailed information about the Archive’s national estimation methodology is available upon request from the National Center for Juvenile Justice.

Table A-3: Content of Case-Level Data sources, 1995


1 County-level intercensal estimates were obtained from the Bureau of the Census for the years 1986-1994. State-level estimates obtained from the Bureau of the Census for 1995 were used to develop 1995 county estimates. The following data files were used:

1980-1989 Preliminary Estimates of the Population of Counties by Age, Sex, and Race. Washington, DC: U.S. Bureau of the Census. 1994.

Estimates of the Population of Counties by Age, Sex, and Race/Hispanic Origin: 1990-1994. Washington, DC: U.S. Bureau of the Census. 1997.

Resident Population Estimates of the U.S. and States by Single Year of Age and Sex: July 1, 1995 Estimates. Washington, DC: U.S. Bureau of the Census. 1996.

2 "Other races" are Asians, Native Americans, and Pacific Islanders. Most individuals of Hispanic ancestry are coded as white.

3 The only information used in this Report that cannot be aggregated by county is data contributed by the Florida Department of Juvenile Justice, which identifies only the district in which each case is handled. To utilize the Florida data, the aggregation criterion is relaxed to include districts. In 1995, there were 3,141 counties in the United States. By replacing Florida’s counties with districts, the total number of aggregation units for this Report becomes 3,085. Therefore, while the report uses the term "county" to describe its aggregation unit, the reader should be aware of the exception introduced by Florida’s data.


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line Juvenile Court Statistics 1995, May 1998