The Crime Scene
Justice Data and the Case of
Multiple Files in GSS 18
Chuck Humphrey
University of Alberta
Atlantic DLI Workshop
April 20-21, 2006
Outline
a. Crime and Victimization Surveys
b. Crime data in the context of the data
reference interview
c. Crime data structures from the context
of the unit of observation
d. Working with GSS 18 as an example
of a survey with multiple files
2
Justice
Data
Justice
System
Data
Police
Courts
(23)
Family
Law
Correctional
Victimization
Population
Data
Justice System Data
• Data collected from administrative
data sources.*
• 11 annual active surveys
• 3 biennial active surveys
• 5 one-time surveys
* See Justice Data Survey List handout.
4
Population Data
• Data collected from the Canadian
population 15 years old and older.
• 1 quinquennial active survey
•
General Social Survey on victimization
• 3 one-time surveys
•
•
•
5
Crime Survey, 1981
Edmonton Crime Survey, 1985
Violence Against Women Survey, 1993
* See the Justice Data Survey List handout.
Data Reference Interview
• Given the variety of Statistics Canada
surveys used to gather information about
crime and our judicial system, let’s review
data reference interview strategies in light
of what we know about justice data.
• A typical data reference interview tries to
distinguish between statistics and data, to
identify likely sources for statistics and data
and to determine how this information can
be accessed.
6
Data Reference Interview
• Is the patron seeking statistics or data?
Statistics are processed
data organized for
display purposes.
Data, which are stored
in files in a specific
structure, require
processing to be
presented or displayed.
7
Statistics
Data
Data Reference Interview
• If the patron is looking for statistics, who or
what agency would publish the numeric
facts or figures that she/he wants?
[Think of statistics as having been published.]
Sources of Statistics:
 Official Statistics
 Government departments or agencies
 Non-official Statistics
 Non-governmental organizations
 Commercial sector sources
8
Data Reference Interview
• What format is most readily available to
retrieve the statistics being sought? In
what format would the patron like to
receive the statistics?
Formats for Statistics:
 Print
 Online
 E-publications
 E-tables
 Databases
9
Data Reference Interview
• If the statistics cannot be found, is there a
data source from which the statistics can
be constructed?
• Occasionally, a data source exists that can
be processed to generate the statistical
information being sought by the patron.
For example, Citizenship & Immigration Canada
produce their Facts & Figures statistical report from the
Landed Immigrant Database System (LIDS). Having
access to LIDS allows one to produce many more tables
than are published in Facts & Figures.
10
Data Reference Interview
• If the patron is looking for data, are they
looking for aggregate data or microdata?
Aggregate data are statistics that have been
organized into a data structure for further
processing. The data structure will be organized
around time, geography, social content or a
combination of these characteristics.
Microdata consist of the information collected from
the objects of the unit of observation and stored in a
data structure for subsequent processing.
11
Data Reference Interview
• Who or what agency would produce and/or
disseminate the data?
[Think of data as having been produced and disseminated.]
• If data are found, how can they be accessed?
Are they available in a public use file or are
the data only available in a confidential file?
• What kind of format does the patron prefer to
work with the data?
12
Data Reference Interview
• Apply the strategies of the data reference
interview with requests for crime or justice
data in Canada.
• Is one more likely to find statistics or data on
justice and crime?
• What kind of data is most likely to be available?
• Who is most likely to publish Canadian justice
statistics?
• Who is most likely to produce and disseminate
Canadian justice data?
13
Data Reference Interview
• Statistics and aggregate data are more
readily available than microdata. The
Canadian Centre for Justice Statistics
(CCJS) compiles results from the surveys
listed above and makes this information
officially available.
• A pilot project is currently underway in the
Research Data Centres to provide access to the
confidential files from the Uniform Crime
Reporting Survey and the Homicide Survey.
14
Data Reference Interview
• For cross-provincial comparisons, CCJS
information has standardized geographies
and a common offence classification
scheme. You may find police services and
provincial justice departments also report
local justice statistics.
For example, the Edmonton Police Service provides
neighbourhood crime statistics on their website. On the
other hand, the office of the Solicitor General of Alberta
refers people to CCJS statistics.
15
Data Reference Interview
• What are your best sources to access
Canadian justice statistics and data?
• Apply the “continuum of access”
Statistics Canada website
provides access to e-tables.
The DSP provides access to
e-publications and E-STAT
access to CANSIM. DLI
provides access to CCJS
tables in Beyond 20/20
format and the GSS. The
Research Data Centres
provide access to some
justice confidential data files.
16
Data Reference Interview
• The Justice Data Survey List handout
includes a column identifying points of
access for products from the various
surveys.
• A more comprehensive list of products is
available from each survey’s IMBD entry.
For the Uniform Crime Reporting Survey, use the
sidebar menu for “Additional Information” and find
entries for the 2004 UCR Survey in the Daily, in
summary tables in Canadian Statistics, in publications
in the online catalogue and in tables from CANSIM.
17
Go to computing exercise
18
Unit of Observation
If it’s data, it has structure.
• One of the defining properties of data
structure is the unit of observation.
• The unit of observation consists of the
objects about which information has been
collected. This information describes each
object and, in a sense, belongs to the
object.
• What are the units of observation in the
active justice surveys mentioned above?
19
Unit of Observation
• Answers can be found in the IMDB entries
for these surveys under the description of
“Target population” and “Instrument design.”
20
Police Administration
Survey
All Canadian municipal,
provincial and federal police
services that were active on
June 15th of the survey year.
Uniform Crime
Reporting Survey
All crimes that come to the
attention of the police.
Unit of Observation
21
Homicide Survey
All homicides that occur in
Canada. Consists of three
main questionnaires:
Incident, Victim and Suspect.
Legal Aid Survey
All legal aid services in
Canada.
Youth Court Survey
All federal statute charges
completed in youth courts of
accused persons aged 12 to
17 years at the time of the
offence.
Unit of Observation
22
Court Resources,
Expenditures and
Personnel Survey
All provincial and territorial
courts and federal courts
comprising the Supreme Court
of Canada, the Federal Court
of Canada, the Tax Court of
Canada and the Office of the
Commissioner for Federal
Judicial Affairs.
Adult Criminal Court
Survey
All federal statute charges in
provincial and supreme
criminal courts in Canada.
Unit of Observation
23
Prosecutorial Services
in Canada
All criminal prosecution
branches in provincial
jurisdictions and of Justice
Canada.
Adult Correctional
Services
All adult correctional
services in Canada.
Corrections Key
Indicators Report for
Adults and Young
Offenders
Counts of adults and youth
in custody of provincial,
territorial and federal
correctional services.
Unit of Observation
24
Youth Custody and
Community Services
All provincial and territorial
youth correctional services.
Alternative Measures
Survey for Youth
All Alternative Measures
cases for youth in Canada.
Maintenance
Enforcement Survey
All cases in maintenance
enforcement programs.
Transition Home
Survey
All residential agencies
serving women victims of
family violence.
Unit of Observation
• With the exception of the UCRS and the
Homicide Survey, for which the confidential
data are now in Research Data Centres,
the information released for all of these
surveys are statistics.
• Aggregate data consist of statistics
organized in a data structure where the unit
of observation is time, geography, a
grouping variable, such as crime category,
or a combination of these.
25
Unit of Observation
• The CANSIM table in Exercise #19 used
time as the unit of observation.
v12397049
v12397057
v12397065
v12397069
1977
5452.16
5201.16
6173.76
5084.05
1978
5180.83
5137.45
6474.76
5294.49
1979
5590.33
5617.12
7019.66
6226.78
1980
5522.79
5805.57
7327.07
6597.85
1981
6266.42
6214.59
7809.78
7004.84
1982
6465.22
6382.96
8089.2
7270.94
1983
6300.42
6114.98
7538.15
7072.82
1984
6206.19
6377.65
7430.11
6733.94
Annual
26
Unit of Observation
Geography can
serve as the unit
of observation.
This table is from
the CCJS series
on the DLI FTP
site (file
crimemun.ivt)
27
Unit of Observation
Here categories
of offences serve
as the unit of
observation.
This is the same
table from the
CCJS series as
the previous
slide but
reshaped.
28
Unit of Observation
• This leaves us with the microdata from the
population surveys on victimization.
• Since 1988, the General Social Survey has
conducted a victimization survey of the
non-institutionalized Canadian population
15 years old and older.
• These data are found in Cycles 3 (1988), 8
(1993), 13 (1999) and 18 (2004).
29
General Social Survey
• Two data files representing separate units
of observation are provided in GSS Cycles
13 and 18. One file is structured around
persons, while the other file is built around
victimization incidents (excluding incidents
of stalking, spousal or ex-spousal
violence).
• In Cycle 18, the person file contains 23,766
individuals and the incident file has 9,824
victimization incidents.
30
General Social Survey
• Each of the public use microdata files has
weight variables to permit generalizations
to individuals and households (in the case
of the main file) or types of incidents (in the
case of the incident file).
• The person file has two weights:
• WGHT_PER : used for person-level estimates
• WGHT_HSD : used to estimate the number of
households with a given characteristic
31
General Social Survey
• The incident file:
• WGHT_VIC : used to estimate the number of
victimization incidents in the population
• WGHT_VIC * NUMINC : used to estimate the
total number of incidents (known as series
reports) with a given characteristic
• ADJWTVIC : used to adjust for series reports
with large numbers, which might otherwise
lead to an inflated estimate of a type of incident
32
General Social Survey
• Three publications to review prior to working
with GSS 18:
• “Criminal Victimization in Canada, 2004”, Juristat
Vol. 25 (7)
• General Social Survey on Victimization, Cycle 18:
Personal safety and perceptions of the criminal
justice system (85-566-X)
• General Social Survey on Victimization, Cycle 18:
An overview of findings (85-565-X)
33