db week3 cj methods
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week3-2.ppt
Concepts, Operationalization, and Measurement
Chapter 4
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Introduction
We want to move from vague ideas of what we want to study to actually being able to recognize and measure it in the real world
Otherwise, we will be unable to communicate the relevance of our idea and findings to an audience
Conceptions and Concepts
Conception: mental image we have about something
Concepts: words, phrases, or symbols in language that are used to represent these mental images in communication
e.g., serious crime
Example of Concept
According to Gottfredson and Hirschi's General Theory of Crime, low levels of self-control is the primary cause of crime. Because self-control is a concept, how to conceptualize and measure it has been debated extensively among academics. Furthermore, the measuring of symptoms of levels of self-control and the inability to measure self-control directly has led some academics to argue that the General Theory of Crime is a tautology and is, therefore, not testable.
Conceptualization
- Conceptualization: mental process of making concepts more precise to specify what we mean
Results in a set of indicators and dimensions of what we have in mind
Indicates a presence or absence of the concept we are studying
Serious crime = offender uses force (or threatens to use force) against a victim
Indicators and Dimensions
Dimension – specifiable aspect of a concept
“Crime Seriousness” – can be subdivided into dimensions
e.g., dimension – victim harm
Indicators – physical injury, economic loss, psychological consequences
Specification leads to deeper understanding
Creating Conceptualization Order
Conceptual definition: working definition specifically assigned to a term, provides focus to our observations
Gives us a specific working definition so that readers will understand the concept
E.g., Which dimensions of SES will be included?
Operational definition: spells out precisely how the concept will be measured
E.g., How will we measure SES?
Progression of Measurement Steps
Conceptualization
Conceptual Definition
Operational Definition
Measurements in the Real World
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Operationalization Choices
Operationalization – the process of developing operational definitions
Moves us closer to measurement
Requires us to determine what might work as a data-collection method
Measurement as “Scoring”
Measurement – assigning numbers or labels to units of analysis in order to represent the conceptual properties
Make observations, and assign scores to them
Different measurement can produce different results
E.g., Time frame in which recidivism is measured might produce different results
Exhaustive and Exclusive Measurement
Every variable should have two important qualities:
Exhaustive – you should be able to classify every observation in terms of one of the attributes composing the variable
Mutually exclusive – you must be able to classify every observation in terms of one and only one attribute
Example – Measure for Marijuana Use
Not exclusive or exhaustive
How many times in the last year have you smoked marijuana?
0
1-3
3-6
6-9
Reworded to be exclusive or exhaustive
How many times in the last year have you smoked marijuana?
0
1-2
3-6
7-9
10 or more times
Levels of Measurement
Nominal: offer names or labels for characteristics (e.g., race, gender, state of residence)
Ordinal: attributes can be logically rank-ordered (e.g., education, opinions, occupational status)
Interval: meaningful distance between attributes (e.g., temperature, IQ score from an intelligence test)
Ratio: has a true zero point (e.g., age, number of priors, sentence length, income)
Implications of Levels of Measurement
Different analytical analysis require certain levels of measurement
Higher levels can be converted to lower levels
Lower levels cannot be converted to higher levels
Therefore, seek the highest level of measurement possible
Criteria for Measurement Quality
Measurements can be made with varying degrees of precision
The more precise, the better
Should not sacrifice accuracy
Reliability
Reliability: whether a particular measurement technique, repeatedly applied to the same object, would yield the same result each time
Problem – even if the same result is retrieved, it may be incorrect every time
Reliability does not insure accuracy
Observer’s subjectivity might come into play
Methods of Dealing with Reliability Issues
Test-retest method – make the same measurement more than once – should expect same response both times
Interrater reliability – compare measurements from different raters; verify initial measurements
Validity
The extent to which an empirical measure adequately reflects the meaning of the concept under consideration
Are you really measuring what you say you are measuring?
Demonstrating validity is more difficult than demonstrating reliability
Methods of Dealing with
Validity Issues
Face validity: on its face, does it seem valid? Does it jibe with our common agreements and mental images?
Criterion-related validity: compares a measure to some external criterion
Construct validity: whether your variables related to each other in the logically expected direction
Multiple measures: compare measure with alternative measures of the same concept
Measuring Crime
- Crime can be a dependent variable in exploratory, descriptive, explanatory, and applied studies
- Crime can also be an independent variable, as in a study of how crime affects fear and other attitudes
- It can be both: the relationship between drug use and other offenses
General Issues in Measuring Crime
How are do you conceptualize crime?
What units of analysis?
Specific entities about which researchers collect information
Offender, victim, offenses, incidents
What purpose? e.g., monitoring, agency accountability, research
Measures Based on Crimes Known to Police
Most widely used measures of crime are based on police records
Certain types are detected almost exclusively by observation (traffic and victimless offenses)
Most crimes reported by victim or witnesses
What crimes are not measured well by police records?
Uniform Crime Reports (UCR)
Originally, reporting voluntary, but now very common
Type I offenses (index crimes/offenses): murder, rape, robbery, larceny, burglary, aggravated assault, motor vehicle theft and arson (added in 1979)
Type II offenses: a compilation of less serious crimes
Summary-based, group level unit of analysis
Assumptions of UCR
Citizens know an offense has occurred
Citizen reports offense to the police
Officer can verify that the offense occurred
Officer decides the offense deserves to be reported
Agency’s numbers end up being forwarded to FBI on time
Positives of UCR
Can compare agencies
Quick, easy, and efficient
Index offenses are valid indicators of public’s crime concerns
Negatives of UCR
Doesn’t count ALL crimes reported to police
Jurisdictions vary in completeness of crime data they provide to FBI; voluntary
Can suffer from clerical, data processing, political problems
Hierarchy rule – only most serious crime counted in an incident
Summary-based measure: UCR data include summary crime counts from reporting agencies
Incident-Based Police Records
Incident-based measures: the incidence of crime is the unit of analysis
Supplementary Homicide Reports (SHR)
Police agencies submit detailed info about individual homicide incidents
Can conduct a variety of studies that examine individual events
National Incident-Based Reporting System (NIBRS)
Joint effort by FBI and BJS to convert UCR to a NIBRS
NIBRS reports each crime incident rather than the total number of certain crimes for each LE agency
Many features are reported individually about each incident, offenses, offenders, victims
UCR – 7 Part I offenses, NIBRS – 46 Group A offenses
Other Revisions with NIBRS
Hierarchy rule dropped
Victim type (individual, business, government, society/public)
Attempted/completed.
Computer-based submission
Drug-related offenses
Computers and crime
Quality control; states require certification
National Crime Victimization Survey (NCVS)
Victimization survey: asks people whether they have been the victim of a crime
Since 1972 by Census Bureau
Sought to illuminate the “dark figure of crime”
Longitudinal panel study: households agree to participate for 3 years (7 interviews; one every 6 months) and then replaced
Does not measure all crime
Respondents are asked screening questions
Positives of NCVS
Measures both reported and unreported crime
Independent of changes in reporting
More information about how crime impacted victim than UCR
Provides more victim characteristics than UCR
Negatives of NCVS
Telescoping incident dates
Faulty memory
Little information on offenders
No information on CJS response if reported
Excludes crimes against commercial establishments
Only includes residents of US
Surveys of Offending
Self-report surveys: ask people about crimes they may have committed
Useful in measuring crimes that are poorly measured by other techniques (prostitution, drug abuse, public order, delinquency)
Useful in measuring crimes rarely reported to police (shoplifting, drunk driving)
Two ongoing self-report studies – NSDUH & MTF
National Survey on Drug Use and Health (NSDUH)
Based on a national sample of households
Conducted since 1971; 2004 sample had n=68,000
Includes questions to distinguish between lifetime use, current use, and heavy use
Encourages candid responses via procedures
Includes residents of college dorms, rooming houses, and homeless shelters
Monitoring the Future (MTF)
Conducted since 1975 by the National Institute on Drug Abuse
Includes several samples of high school students and others, totaling about 50,000 respondents each year
Questions concern self-reported use of alcohol, tobacco, illegal drugs, delinquency, other acts
A subset of 2,400 MTF respondents receive follow-up questionnaire
Composite Measures
Allows us to combine individual measures to produce more valid and reliable indicators
Typology: produced by the intersection of two or more variables to create a set of categories or types
e.g., Typology of Delinquent/Criminal Acts (Time 1 and 2)
None, Minor (theft of items worth less than $5, vandalism, fare evasion), Moderate (theft over $5, gang fighting, carrying weapons), Serious (car theft, breaking and entering, forced sex, selling drugs
Nondelinquent, Starter, Desistor, Stable, Deescalator, Escalator
Index of Disorder
What is disorder? (Skogan, 1990)
Distinguish b/w physical presence & social perception
Physical disorder: abandoned buildings, garbage and litter, graffiti, junk in vacant lots
Social disorder: groups of loiterers, drug use and sales, vandalism, gang activity, public drinking, street harassment
Index created by averaging scores for each measure
