Measuring
Delinquency
CRIM 302
Sources for Measuring Crime &
Delinquency
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Official Data=Archived data held by an
institution or agency
– Examples: Uniform Crime Reports, Juvenile Court
Data
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Self-Report Data=Information received from
the subjects under study
– Self-Reported Victimization: National Crime
Victimization Survey
– Self-Reported Delinquency: National Youth Survey
Ways of Measuring Crime &
Delinquency
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Raw Numbers: Simple count of individual events
Rates: Sum of Individual Events Compared to
Population at Large
No. of Crimes * 100,000=# Crimes/100,000 in population
No. of People in Population
– Allows for accurate comparison across groups, locations,
etc.
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Percent Change: Proportion of change in individual
events from one time to another
T2-T1 * 100%= % Percent change from Time 1 to Time 2
T1
Computation Examples
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5000 crimes committed in community of
500,000 people
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–
–
–
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(500/500,000) * 100,000
.001 *100,000
100 crimes/100,000 people
Or .001*1000=1 crime/1000 people
Crime in 2002=1000; crime in 2003=500
– ((500-1000)/1000) *100%
– (-500/1000)*100%
– (-.5) *100%=50% decrease in crime
Interpreting the Numbers
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Tyranny of small numbers
– Small increase in small numbers results in
large percentage increases
– 100 crimes
• 10 juveniles +7  Increase 70%
• 90 adults  +45  Increase 50%
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Impact of crime and actual nature of the
trend can be easily exaggerated
Other Misleading Uses of Data
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Long-term trends v. short-term trend
– Short-term increase may not be dramatic if
viewed in the long-term
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Comparisons
– Using the lowest points as a base year for
comparison
– Not using a comparison group
Official Data: Uniform Crime
Reports
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The Federal Bureau of Investigation (FBI) began collecting data
from law enforcement agencies on number of crimes reported to
police in 1929
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The UCR covers over 95% of the United States and reports:
– No. of Crimes Reported to Police
– No. & characteristics of Offenders Arrested
– No. of Crimes Cleared by Police
– Additional Information Provided about Homicide, Police
Department Characteristics, Crime Consequences
Substance of the UCR
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UCR represents one of two primary
measures of crime trends for the U.S.
 Index and Non-Index Crimes
 Index Crimes Partitioned into 2 Parts
– Violent Crimes: Murder/Manslaughter; Aggravated
Assault; Robbery; Rape
– Property Crimes: Burglary, Motor Vehicle Theft,
Larceny, Arson
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http://www.fbi.gov/ucr/ucr.htm
Strengths
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Best measure of crime across the nation that
we currently have
Validity for certain crimes
Problems tend to be stable over time,
allowing trends and patterns to surface
Easy to access and inexpensive
Allows for city and regional trend
comparisons
Provides detailed information on reporting
patterns, who is arrested, and homicides
Weaknesses
Doesn’t capture unreported crime--validity
 Only most serious crime is reported
 Does not include federal offenses
 No. arrested is not equal to the actual number of
youths who committed crime—group arrests
overestimate juvenile crime
 UCR is based on summary data that does not allow
closer inspection into each arrest
 Quality of data questionable:
– Underreporting/overreporting by law enforcement
– Variability of police practices/Use of arrest
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Future of the UCR
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The National Incident-Based Reporting
System
– Launched by the FBI in 1988 for eventual replacement of the
Uniform Crime Reports system
– Collects a wide range of information on victims, offenders, and
circumstances for more offenses than the UCR
– Offenses tracked in NIBRS include violent crimes (e.g., homicide,
assault, rape, robbery), property crimes (e.g., theft, arson,
vandalism, fraud, embezzlement), and crimes against society (e.g.,
drug offenses, gambling, prostitution).
– Collects information on multiple victims, multiple offenders, and
multiple crimes that may be part of the same episode.
– Not yet representative across the country—In 1997, 12 States
were participating
Victimization
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Two primary sources of data: National Crime Victimization Survey and the
National Incident-Based Reporting System
The National Crime Victimization Survey (NCVS)
– Victim self-report survey conducted by the U.S. Department of Commerce,
Bureau of the Census on behalf of the U.S. Department of Justice, Bureau
of Justice Statistics for the past 20 years
Data obtained from a nationally representative sample of roughly 43,000
households comprising nearly 100,000 persons
– Remain in sample for 3 years
– Interviewed every 6 months
All individuals 12 and older are interviewed about the frequency, characteristics
and consequences of criminal victimizations they experienced within a particular
time frame
Examines the following crimes: Rape, sexual assault, robbery, assault, theft,
household burglary, and motor vehicle theft
Use data to compare with UCR trends as well as estimate the likelihood of
victimization for the population and segments of the population (e.g., women,
the elderly, members of various racial groups, city dwellers, or other groups)
http://www.ojp.usdoj.gov/bjs/pub/pdf/cv02.pdf
Sources: Finkelhor, D. & Ormrod, R. (2000). Characteristics of Crimes Against Juveniles. Washington, DC: Department of Justice, Office of
Juvenile Delinquency & Prevention; National Crime Victimization Survey; National Incident-Based Reporting System
Strengths of NCVS
Allows “check” of UCR (NCVS
specific)—measures “dark figure of
crime”
 Collects a lot of information necessary
to understand crime and victimization
but not found in official crime reports
 Not subject to political agendas
(necessarily)
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Weaknesses of NCVS & SelfReport
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Lying
Exaggeration/Embarrassment
Memory and accurate time period
Cost and accessibility
Hidden Populations or missing populations
Inaccurate information
Administration of the Interview (face to face v.
phone)
Refusal rates
Self-Report Data
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Monitoring the Future
– Random sample of schools
– 12th graders in each selected school participate
– Sub-sample is followed over time
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National Youth Survey: Longitudinal, cohort study of juveniles
throughout the teen-age years
– Started 1976 with 1725 11-17 year olds who were followed until 1993 (27-33
years old)
– Measured delinquency, victimization, and various theoretical variables
– Provide much more information about the various relationships
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The Youth Development Study
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– Recent effort to follow cohorts of youth in Richmond, VA, Denver, CO, and
Rochester, NY
– High-risk youth samples
http://ojjdp.ncjrs.org/ccd/rochester.html
Self-Report Differences
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Contrary to arrest rates, there was no sharp increase in violence in selfreport data, indicating arrest data may have exaggerated violent crime
trend
Attention to the role of enforcement trends, discrimination, and
paternalism
More youth commit crime than are arrested
Females commit crime at a rate more similar to males than seen in
official statistics
The more delinquent a youth is, the greater the likelihood he/she will be
victimized
Socioeconomic status is a better predictor of delinquency than race—
the offending differential reduces substantially when SES is accounted
for