2. •Causation, units, and time are key elements in
planning a research study
•As social scientists, we seek to explain the
causes of some phenomenon (e.g., crime)
•Who are what we are studying is an important
part of research
•Researchers also must consider the time order
of events
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3. 3
•Causation is the focus of explanatory
research
•Cause in social science is inherently
probabilistic
•Certain factors make crime/delinquency more or
less likely within groups of people
•Two models of explanation
•Ideographic – Lists the many, perhaps unique
considerations behind an action
•Nomothetic – Lists the most important (and
fewest) considerations/variables that best
explain general patterns of cause and effect
4. •Posited by Shadish, Cook, & Campbell (2002)
•Empirical relationship between variables
•Temporal order (cause precedes effect)
•No alternative explanations – no spurious other
variable(s) affecting the initial relationship
•Any relationship that satisfies all these criteria
is causal
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5. •Within the probabilistic model, two types:
•Necessary cause – Represents a condition that
must be present for the effect to occur (e.g.,
being charged is necessary cause to be
convicted)
•Sufficient cause – Represents a condition that,
if it is present, will pretty much guarantee that
the effect will occur (e.g., pleading guilty is
sufficient cause to being convicted)
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6. •Scientists assess the truth of statements about
cause by considering threats to validity.
•When we make a cause-and-effect statement,
we are concerned with its validity – whether it
is true and valid
•Certain threats to the validity of our inference
exist
•These are reasons why we might be incorrect
in stating that some cause produces some
effect
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7. •Refers to our ability to determine whether a
change in the suspected cause is statistically
associated with a change in the suspected
effect
•Are two variables related to each other?
•Researchers cannot have much confidence in
statements about cause if their findings are
based on a small number of cases
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8. •An observed association between two variables
has internal validity if the relationship is, in
fact, causal and not due to the effects of one or
more other variables
•Generally due to non-random or systemic
error
•The threat to IV results when the relationship
between two variables arises from the effect of
some third variable
•Example: drug users sentenced to probation over
prison recidivate less
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9. •Concerned with whether research findings in
one study can be replicated in another study,
often under different conditions
•Do the findings apply equally in different
settings (locales, cities, populations)?
•Kansas City evaluation found sharp reductions
in gun-related crimes in hot spots that had
been targeted for focused police patrols
•Indianapolis and Pittsburgh launched similar
projects
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10. •Concerned with how well an observed
relationship between variables represents the
causal process
•Refers to generalizing from what we observe
and measure to the real-world things in which
we are interested
•e.g., close supervision of officers more tickets?
•e.g., Kansas City Preventive Patrol Experiment,
“police visibility”
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11. •The four types of validity threats can be
grouped into these two categories
•Bias – Internal Validity and Statistical
Conclusion Validity threats are related to
systematic and nonsystematic bias
•Generalizability – Construct Validity and
External Validity are concerned with
generalization to real-world behaviors and
conditions
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12. •Temporal order: which comes first?
•A statistical relationship exists, but underlying
causes affect both drug use and crime (Internal
Validity threat)
•What constitutes drug use? Crime?
(Construct Validity threat)
•How will policy affect drug use and crime?
•A crackdown on all drugs among all populations
will do little to reduce serious crime
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13. •Bridges idiographic and nomothetic
approaches to explanation by seeking to
understand how causal mechanisms operate in
specific contexts
•Studies how such influences are involved in
cause-and-effect relationships
•Exhibits both ideographic & nomothetic
approaches to explanation
•"Can the design of streets and intersections be
modified to make it more difficult for street
drug markets to operate?"
14. •What or who is studied
•Individuals - Police, victims, defendants, inmates,
gang members, burglars, etc.
•Groups - Multiple persons with same characteristics
(gangs, cities, counties, etc.)
•Organizations - Formal groups with established
leaders and rules (prisons, police departments,
courtrooms, drug treatment facilities, etc.)
•Social artifacts - Products of social beings and their
behavior (stories in newspapers, posts on the
Internet, photographs of crime scenes, incident
reports, police/citizen interactions)
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15. •Ecological fallacy - Danger of making assertions
about individuals based on the examination of
groups or aggregations
•Poor areas = more crime, therefore poor people
commit more crime
•Individual fallacy – Using anecdotal evidence to
make an argument
•O.J. Simpson court resources
•Reductionism - Failing to see the myriad of
possible factors causing the situation being
studied
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16. •Time sequence is critical in determining
causation
•Time is also involved in the generalizability of
research findings
•Observations can either be made more or less
at one point, or stretched over a longer period
•Observations made at more than one time point
can look forward or backward
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17. •Observing a single point in time (cross-section)
•Simple and least costly way to conduct research
•Typically descriptive or exploratory in nature
•A single wave of the National Crime
Victimization Survey (NCVS) is a descriptive
cross-sectional study that estimates how many
people have been victims of crime in a given
time
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18. •Permit observations over time
•Trend – Those that study changes within some
general population over time (UCR)
•Cohort – Examine more specific populations as
they change over time (Wolfgang study)
•Panel – Similar to trend or cohort, but the same
set of people is interviewed on two or more
occasions (NCVS) (panel attrition)
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19. •Gun ownership and violence study by Swiss
researcher Martin Killias (1993)
•Compared rates of gun ownership as reported in an
international crime survey to rates of homicide and
suicide committed with guns
•May be possible to draw approximate
conclusions about processes that take place over
time, even when only CS data is available
•When time order of variables is clear, logical
inferences can be made about processes taking
place over time
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20. •Asks people to recall their past for the purpose
of approximating observations over time
•People have faulty memories; people lie
•Analysis of past records also suffer from
problems – records may be unavailable,
incomplete, or inaccurate
•Prospective research – longitudinal study that
follows subjects forward in time (Widom – child
abuse/drug use)
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21. •Cross-sectional study = snapshot – an image at
one point in time
•Trend study = slide show – a series of
snapshots in sequence over time, allows us to
tell how some indicator varies over time
•Panel study = motion picture – gives
information about individual observations over
time
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