Appendix A Methods
Juvenile Court Statistics (JCS) uses
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
by 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.
Courtlevel aggregate statistics either are
abstracted from the annual reports of
state and local courts or are contributed directly to the Archive.
Courtlevel 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 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, gender, 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 jurisdictions data into a common case-level format.
The aggregation of these
standardized case-level data files constitutes
the Archives national case-level
database. The compiled data from
jurisdictions that contribute only courtlevel statistics constitute the national
court-level database. Together, these
two multijurisdictional databases are
used to generate the Archives national estimates of delinquency cases and
to provide the sample of petitioned
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.
Table A–1: 1999 Stratum
Profiles for Delinquency Data |
|
|
|
Counties
reporting compatible datah
|
Stratum
|
County
population ages 1017 |
Counties
in stratum |
Number
of Counties
|
|
Case-
level |
Court-
level |
Total*
|
Percentage
of juvenile population |
|
1 |
Less than 10,745 |
2,549 |
1,447 |
249 |
1,665 |
64% |
2 |
10,74545,940 |
388 |
192 |
53 |
227 |
61 |
3 |
45,941111,220 |
112 |
58 |
14 |
68 |
63 |
4 |
More than 111,220 |
36 |
30 |
8 |
32 |
92 |
Total |
|
3,085 |
1,727 |
324 |
1,992 |
70 |
* Some counties reported both case-level and court-level data; therefore,
the total number of counties reporting delinquency data is not equal to
the number of counties reporting case-level data plus the number of counties
reporting court-level data. |
|
Table A2: 1999 Stratum
Profiles for Status Offense Data |
|
|
|
Counties
reporting compatible data
|
|
|
|
Number of counties
|
|
Stratum
|
County population ages 1017 |
Counties in stratum |
Case- level |
Court- level |
Total
|
Percentage of juvenile population |
|
1 |
Less than 10,745 |
2,549 |
1,534 |
184 |
1,718 |
66% |
2 |
10,74545,940 |
388 |
190 |
34 |
224 |
60 |
3 |
45,941111,220 |
112 |
47 |
10 |
57 |
54 |
4 |
More than 111,220 |
36 |
30 |
1 |
31 |
90 |
Total |
|
3,085 |
1,801 |
229 |
2,030 |
68 |
|
In 1999, case-level data describing
972,138 delinquency cases handled
by 1,727 jurisdictions in 29 states met
the Archives criteria for inclusion in
the development of national estimates. Compatible data were available from Alabama, Alaska, Arizona,
Arkansas, California, Connecticut,
Florida, Illinois, Kentucky, Maryland,
Minnesota, Mississippi, Missouri,
Montana, Nebraska, Nevada, 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
62% of the nations juvenile population in 1999. Compatible court-level
aggregate statistics on an additional
100,964 delinquency cases from 324
jurisdictions were reported from the
District of Columbia and the states of
California, Hawaii, Idaho, Illinois,
Indiana, New York, Oklahoma, and
Vermont. In all, the Archive received
compatible case-level data and courtlevel statistics on delinquency cases
from 1,992 jurisdictions containing
70% of the nations juvenile population in 1999 (table A1).
Case-level data describing 92,890
formally handled status offense cases
from 1,801 jurisdictions in 29 states
met the criteria for inclusion in the
sample for 1999. The contributing
states were Alabama, Alaska, Arizona,
Arkansas, California, Connecticut,
Florida, Illinois, Indiana, Kentucky,
Maryland, Minnesota, Mississippi,
Missouri, Montana, Nebraska,
Nevada, New York, North Dakota,
Ohio, Pennsylvania, South Carolina,
South Dakota, Tennessee, Texas,
Utah, Virginia, Washington, and West
Virginia. These courts had jurisdiction over 60% of the juvenile population. An additional 229 jurisdictions
in 6 states (California, Hawaii, Idaho,
Indiana, Oklahoma, and Vermont) and
the District of Columbia reported
compatible court-level aggregate
statistics on 9,341 petitioned status
offense cases. Altogether, compatible
case-level and court-level data on
petitioned status offense cases were
available from 2,030 jurisdictions
containing 68% of the U.S. juvenile population in 1999 (table A2).
Additionally, petitioned status offense case
profiles in the Report include case-level
data describing 612,835 cases and
court-level aggregate data describing
85,973 cases for the years 1990
through 1998.
Juvenile Population
The volume and characteristics of
juvenile court caseloads are partly a
function of the size and demographic
composition of a jurisdictions
population. Therefore, a critical element in
the Archives development of national
estimates is the population of youth
that generate the juvenile court referrals in each jurisdictioni.e., the
juvenile population of every U.S. county.
A survey of the Archives case-level
data shows that very few delinquency
or status offense cases involve youth
younger than 10. Therefore, the lower
age limit of the juvenile population 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 and 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 juvenile population 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
juvenile population is the number of
youth residing in a county who are
between the ages of 10 and 15.
The juvenile population estimates
used in this Report were developed
with data from the Bureau of the
Census.1 The estimates, separated into
single-year age groups, reflect 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 by
using the national case-level database, the national court-level database, and the Archives juvenile
population 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 Archives 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: the
courts jurisdictional responsibilities (upper age); the size and demographic composition of the community; the
age, gender, 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 in reporting 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 juveniles 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, juvenile population
estimates are developed for nine agebyrace categories in each stratum of
counties.
The next step is to identify within
each stratum the jurisdictions that
contributed to the Archive case-level
data consistent with
JCS
reporting
requirements. The national case-level
database is summarized to determine
within each stratum the number of
court cases that involved youth in
each of the nine age/race population
groups. Case rates (number of cases
per 1,000 juveniles in the population)
are developed for the nine age/race
groups within each of the four strata.
For example, assume that a total of
2,517,000 white youth between the
ages of 10 and 15 resided in the
stratum 2 counties that reported case-level
data to the Archive. If the Archives
case-level database shows that the
juvenile courts in these counties handled 46,163 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 2 would be 18.3, or:
(46,163/2,517,000) x 1,000 = 18.3
Comparable analyses are then used
to establish the stratum 2 case rates
for black youth and youth of other
races in the same age group (58.6 and 18.6, respectively).
Next, information contained in the
national court-level database 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 stratums nine age/race
case rates (developed from the caselevel data) are paralleled in the aggregate statistic.
For example, assume that a
jurisdiction in stratum 2 with an upper age of
15 processed 600 cases during the
year and that this jurisdiction had a
juvenile population of 12,000 white
youth, 6,000 black youth, and 2,000
youth of other races. The stratum 2
case rates for each racial group in the
1015 age group would be multiplied
by the corresponding population to
develop estimates of the proportion
of the courts caseload that came
from each age/race group, as follows:
White:
(18.3 x 12,000) / [(18.3 x 12,000) +
(58.6 x 6,000) + (18.6 x 2,000)] = 0.36
Black:
(58.6 x 6,000) / [(18.3 x 12,000) +
(58.6 x 6,000) + (18.6 x 2,000)] = 0.58
Other:
(18.6 x 2,000) / [(18.3 x 12,000) +
(58.6 x 6,000) + (18.6 x 2,000)] = 0.06
The jurisdictions total caseload of
600 would then be allocated based on
these proportions. In this example,
36% of all cases reported in the
jurisdictions aggregate statistics involved
white youth, 58% involved black
youth, and the remaining 6% 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 216 white youth, 348 black
youth, and 36 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 juvenile
population figures for the entire sample
are also compiled. Together, the case
counts and the juvenile population
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 juvenile
population 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 Archives
national case-level database. For example, assume that the Archive generates an estimate of 43,970 petitioned
delinquency cases involving white 16-year-olds from stratum 2 juvenile
courts. Assume also that the national
case-level database for that year
contained 21,891 petitioned delinquency
cases involving white 16-year-olds
from stratum 2 counties. In the
Archives national estimation database,
each stratum 2 petitioned delinquency case that involved a white 16-yearold would be weighted by 2.01, because:
43,970/21,891 = 2.01
The final step in the estimation
procedure is to impute missing data on
individual case records. Table A3
indicates the standardized data elements
that were available from each
jurisdictions 1999 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 characteristicsof cases with similar case
attributes (i.e., the age, gender, and
race of the youth; the offense charged;
and the courts decisions on detention, petition, adjudication, and
disposition).
More detailed information about the
Archives national estimation methodology is available upon request from
the National Center for Juvenile Justice.
Table A3:
Content of Case-Level Data Sources, 1999 |
Data Source |
Age at referral
|
Gender |
Race |
Referral source
|
Referral reason
|
Secure detention
|
Manner of handling
|
Adjudication
|
Disposition
|
|
Alabama |
AL |
AL |
AL |
AL |
AL |
AL |
AL |
AL |
AL |
Alaska |
AK |
AK |
AK |
|
AK |
AK |
AK |
AK |
AK |
Arizona |
AZ |
AZ |
AZ |
AZ |
AZ |
AZ |
AZ |
AZ |
AZ |
Arkansas |
AR |
AR |
AR |
|
AR |
|
AR |
AR |
AR |
California |
CA |
CA |
CA |
CA |
CA |
CA |
CA |
CA |
CA |
Connecticut |
CT |
CT |
CT |
CT |
CT |
|
CT |
CT |
CT |
Florida |
FL |
FL |
FL |
|
FL |
|
FL |
FL |
FL |
Illinois1 |
IL |
IL |
IL |
IL |
IL |
IL |
IL |
IL |
IL |
Kentucky |
KY |
KY |
KY |
|
KY |
|
KY |
|
|
Maryland |
MD |
MD |
MD |
MD |
MD |
|
MD |
MD |
MD |
Minnesota |
MN |
MN |
MN |
MN |
MN |
|
MN |
MN |
MN |
Mississippi |
MS |
MS |
MS |
MS |
MS |
MS |
MS |
MS |
MS |
Missouri |
MO |
MO |
MO |
MO |
MO |
MO |
MO |
MO |
MO |
Montana |
MT |
MT |
MT |
MT |
MT |
|
MT |
MT |
MT |
Nebraska |
NE |
NE |
NE |
NE |
NE |
NE |
NE |
NE |
NE |
Nevada |
NV |
NV |
NV |
|
NV |
NV |
NV |
NV |
NV |
New Jersey |
NJ |
NJ |
NJ |
|
NJ |
|
NJ |
NJ |
NJ |
New York |
NY |
NY |
|
NY |
NY |
NY |
NY |
NY |
NY |
North Dakota |
ND |
ND |
ND |
ND |
ND |
|
ND |
ND |
ND |
Ohio2 |
OH |
OH |
OH |
OH |
OH |
OH |
OH |
OH |
OH |
Pennsylvania |
PA |
PA |
PA |
PA |
PA |
|
PA |
PA |
PA |
South Carolina |
SC |
SC |
SC |
SC |
SC |
SC |
SC |
SC |
SC |
South Dakota |
SD |
SD |
SD |
|
SD |
SD |
SD |
SD |
SD |
Tennessee |
TN |
TN |
TN |
TN |
TN |
TN |
TN |
TN |
TN |
Texas |
TX |
TX |
TX |
TX |
TX |
|
TX |
TX |
TX |
Utah |
UT |
UT |
UT |
UT |
UT |
|
UT |
UT |
UT |
Virginia |
VA |
VA |
VA |
|
VA |
|
VA |
|
VA |
Washington |
WA |
WA |
WA |
WA |
WA |
|
WA |
WA |
WA |
West Virginia |
WV |
WV |
WV |
WV |
WV |
WV |
WV |
|
WV |
Percentage of estimation sample |
99% |
100% |
94% |
69% |
97% |
36% |
100% |
91% |
92% |
Note: The symbol indicates that compatible
data for this variable are not reported by this state.
1 Data from Cook County only.
2 Data from Cuyahoga County only. |
|
1 County-level intercensal estimates
were obtained from the Bureau of the
Census for the years 199099. The
following data files were used:
U.S. Bureau of the Census. 2001.
Estimates of the Population of Counties by
Age and Gender: 19901999 [
machinereadable data file]. Washington, DC: U.S.
Bureau of the Census.
U.S. Bureau of the Census. 2001.
Estimates of the Population of Counties by
Age, Sex, and Race/Hispanic Origin:
19901999 [machine-readable data file].
Washington, DC: U.S. Bureau of the
Census.
2 Other races are Asians, American
Indians, 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 use the
Florida data, the aggregation criterion is
relaxed to include districts. In 1999,
there were 3,141 counties in the United
States. By replacing Floridas 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 made for Floridas
data.
|