Transcript Chapter 2a Powerpoint

Criminal Violence: Patterns,
Causes, and
Prevention
Riedel and Welsh, Ch. 2
“Measures of Violence”
OUTLINE
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Why are measures of crime important?
Crime Rates v. Amounts
Uniform Crime Reports (UCR)
National Incident-Based Reporting System
(NIBRS)
National Crime Victimization Survey (NCVS)
Introduction
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We need reliable data about violent crime in
order to inform:
(a) public policy
(b) research about violence (e.g., patterns, trends,
locations).
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Each source of data has certain strengths and
limitations. None is perfect.
To be able to use or understand such data, it
is necessary to be aware of major strengths
and weaknesses.
Why Are Measures of Crime
Important?
Measures are needed to answer important policy
questions.
2.
Tripartite perspective: Need measures of crime to
assess patterns.
3.
Need to distinguish “opinions” v. “facts” or
“evidence” (social construction)
Example:
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Q: Is violent crime going up or down?
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A: Answer depends on: 1) the type of measure
used, 2) type of crime, 3) time period, 4) rates v.
raw numbers.
1.
Crime Rates v. Amounts
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The amount is how much violent behavior
there is, defined by location and time span.
Crime rates are ratios of amounts to the
total population.
Crime rates have five components:
1.
2.
3.
4.
5.
amount of the crime
population at risk for that crime
a constant multiplier such as 100,000
location
time span
Crime Rate = (Amount / Population at Risk) ×
100,000
Crime Rates v. Amounts (cont.)
Example: similar amounts of murder, different populations.
There were 510 murders in Chicago and 523 murders in
New York in 2008. Which city had the greatest risk of
murder victimization?
If we “plug in” the numbers, we have the following 2008
murder victimization rates:
(New York) 6.26 = (523/ 8,345,075) * 100,000
(Chicago) 18.02= (510/ 2,829,7304) * 100,000
Persons living in Chicago have a risk of being murdered
that is almost 3 times higher than the risk for people living
in NY.
While the amount of murders for the two cities is similar,
the rate of victimization is dramatically different.
Crime Rates & Amounts (cont.)
Example: similar populations, different rates:
There were 23 murders in Austin, Texas, and 234 murders
in Baltimore, Maryland, in 2008. Which city had the
greatest risk of murder victimization, even though they had
similar populations?
If we “plug in” the numbers, we have the following 2008
murder victimization rates:
(Austin) 3.05 = (23/ 753,535) * 100,000
(Baltimore) 36.87= (234/634,549) * 100,000
Persons living in Baltimore have a risk of being murdered
that is almost 12 times higher than the risk for people living
in Austin.
While the populations for the two cities are similar, the murder
victimization rates are dramatically different.
Uniform Crime Reports (UCR)
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There are over 17,000 city, county, and state law
enforcement agencies reporting to the UCR
program directly or through state agencies.
http://www.fbi.gov/ucr/ucr.htm
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Part I offenses (“Index” offenses) are divided into
crimes against the person (criminal homicide,
forcible rape, robbery, aggravated assault, and
arson) and crimes against property (burglary,
larceny-theft, motor vehicle theft).
Part II offenses include 21 other offenses, such as
fraud, embezzlement, weapons offenses, and
simple assault.
Uniform Crime Reports (cont.)
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While a number of forms are required by the UCR
program, three are most relevant to violent crime:
1.
2.
3.
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Return A
Age, Sex, Race, and Ethnic Origin of Arrested Offenders
Supplementary Homicide Report
The process of collecting information about violent
crime begins with a complaint to law enforcement
officials, who investigate and determine whether a
criminal offense has occurred (Figure 2.1, p. 28).
Figure 1
Uniform Crime Reporting Program
Violent
Crime
Police
Department
Police
Records
Report Directly
to UCR
UCR
Forms
Other
Information
State Uniform
Crime Reporting
Agency
Return A Crimes Known to
the Police
Age, Sex, Race,
& Ethnicity of
Arrested Offenders
Uniform Crime
Reporting
Program
Crime in the
United States
State
Uniform Crime
Reports
Supplementary
Homicide
Reports (SHR)
National Incident-Based Reporting
System (NIBRS)
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The UCR has been subject to criticism from
the 1950s onward.
NIBRS was created to address several
limitations of the UCR.
http://www.ojp.usdoj.gov/bjs/nibrs.htm
UCR v. NIBRS
UCR NIBRS
DETAIL ON INCIDENTS?
NO
YES
LINKS VICTIMS W/
OFFENDERS?
HIERARCHY RULE?
NO
YES
YES
NO
INFORMATION LINKING
NO
INCIDENTS & OFFENDERS?
YES
ACCOUNTS FOR OFFENSES NO
ATTEMPTED V.
COMPLETED?
YES
National Crime Victimization Survey
The National Crime Survey began in 1972. In
1991, it was redesigned and retitled the National
Crime Victimization Survey (NCVS).
http://www.ojp.usdoj.gov/bjs/pubalp2.htm#cvus
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Crime surveys, unlike information collected
from police, rely on interviews with victims.
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One purpose of crime surveys is to get an idea of
how much crime occurs that is not reported to or
by the police.
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Crime rates estimated by the UCR are only
about one half to one third of those based on
victim reports.
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NCVS (cont.)
How are Incidents Collected?
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The NCVS collects victimization data from a nationally
representative sample of about 100,000 individuals age 12
or older living in about 50,000 U.S. households. Interviews
are translated for non-English-speaking respondents. The
interview takes about ½ hour.
What is Collected?
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There are two steps in interviewing victims:
1.
2.
Screening questions are asked to determine whether the
respondent has been the victim of a crime in the past 4 months.
If the respondent says that someone in the household has been a
victim, then an individual victimization report is completed for
each incident mentioned in response to the screening questions.
NCVS (cont.)
In addition to estimating the number of victimizations, the
NCVS gathers details on each incident:
 Characteristics of the victim (age, sex, race, ethnicity,
marital status, income, and educational level)
 Characteristics of the offender (sex, race, and approximate
age)
 Relationship between victim and offender
 Month, time, and location of the crime
 Self-protective actions taken by the victim during an
incident and results of those actions
 Consequences of the victimization, including any injury or
property loss
 Whether the crime was reported to police; reasons for
reporting/not reporting
 Offender use of weapons, drugs, and alcohol
Limitations of the NCVS
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Cost of Large Samples. To get reliable estimates, a very
large number of people must be sampled.
Poor Memory and Telescoping. The longer the time
between the actual victimization and the interview, the
greater the likelihood of memory failure. There is a
danger of telescoping: a victimization that occurred
outside the requested time span is mistakenly recalled
as occurring within the last 6 months.
Errors in Reporting
 Mistaken reporting: respondent believes he or she
was the victim of a crime but was not.
 Sampling bias: Potential undercounting of young
people, males, and members of minority groups