Quasi experiemtal designs and field research
Variations in classical experiments • Post test only designs • Used when pretesting might affect the results • To assess this could use a 4 group design, experimental pre-post • Experimental post • Control pre-post • Control post
Non-equivalent groups • Comparison group rather than control group (difference is random assignment) • Use of matching • Widom’s study of child abuse and criminality • Abused matched with a non-abused group on gender, race, age, and SES • Problem with matching
Non-equivalent • Predicting parole risk • Use of LSI • 3 jails, one (comparison) not informed of LSI scores • In all groups, LSI predictive of further recidivism • Jails who knew LSI scores released more low risk offenders
Non-equivalent • Telephone service areas with caller ID compared to those without services to observe effects on obscene phone calls • Would be deceptive if there are differences in obscene phone calls from area to area—probably not the case • Less complaints in caller ID areas
Cohorts • Using a particular group that all begin at the same time, compare to a group that began at another time. Make assumption of equivalence • i.e., compare graduate students who started in 2003 with those who started in 2004 • Police class, those sentenced to probation in a particular month, etc.
Time series designs • Interrupted time series design • Take baseline data, make an intervention, collect data • See p. 196 • First example, general trend, not clear that the intervention made a difference • Current downward trend in crime
Time series • Second pattern: random fluctuation • 3rd pattern: immediate effect (in this example, incapacitation) • 4th pattern: more gradual effect (deterrence?) • Interrupted time series with nonequivalent comparison group
Time series • Time series design with switching replications • If similar changes occur in DV in different places at different times, corresponding to when the intervention was introduced, it makes it likely that the IV did affect the DV
Field research • Best for topics that can best be understood in their natural setting • Example: nonverbal behaviors • Relationship between environmental design and crime requires observation of the environment • Pedestrians before and after street lighting was enhanced
Types of participation • Full participant (deception, may affect what is going on, safety issues, incompatibility) • Observing around the periphery of criminal activity • Observer-as-participant: identifies self as research, interacts with subjects • Police patrol studies (ride along)
Types of participation • Going native problem • Complete observer, not part of the action in any way. May be unobtrusive, or might identify oneself as a research, but no interaction • Less able to ask questions
Observation • Observe, sometimes ask questions • Questions are often more spontaneous, unstructured “informal conversational interview” • Listening and probes
Gaining access • Formal organizations • Sponsor, letter, phone call, meeting • Gaining access to subcultures • Sponsor/informant • May be people working with criminals, such as caseworkers, police, probation, lawyers, private investigators, treatment centers, ex-offenders, hangouts
Selecting subjects • Snowball sampling • Potential biases, i.e., only people who have been caught or treated • Purposive sampling, sampling dimensions • Group, location, time, weather
Recording observations • Cameras to take photos • Video recordings • Tape recorders • Field notes—what we know, what we think happened • Sketchy notes, expand later, write out everything • Unstructured observation
Recording observations • Structured observations • Instruments to guide observations • Environmental surveys (BJA), may be used to plan strategies • Other observations • Possibilities listed, recorded with details as they happen
Combining with other data • Linking research methods • i.e., combining observational studies of neighborhoods with surveys of resident perceptions and crime statistics
Examples of studies • Shoplifters • How much? How much is identified? • Participant observation—participants pretended to be shoppers • # shoppers who stole divided total # of shoppers • Sampled days and times
Shoplifters • Everyone who entered the store was counted • Systematic random sampling used to select subjects • Subjects followed and observed • # thefts divided by the total observed
shoplifters • To determine detection rates, research staff were used as confederate shoplifters and some of them were observed by research staff assigned to make observations (double blind) • Reliability of observers could thus be assessed • Reliability could then be used to adjust shoplifting rates
Other studies • Seat belts—how many people where seat belts? • Sampled time of day, type of road and observation site, density of auto ownership • Explicit instructions p. 307
Racial profiling • Problem with comparing race of drivers stopped with race of distribution for a resident population (i.e., more non-residents may be stopped) • Estimate of drivers by observing race from toll booths • Estimate of # of cars eligible to be stopped
Profiling • Having observers drive 5 miles over speed limit, count the number speeding and their race • Lambeth’s study—blacks 13.5% of drivers, 15% of those speeding. 35% stopped were black and 73% of those arrested after the stop were black. • However, speeding not the only violation
Profiling • Lange study—examined only cases going 15 or more miles over the speed limit • Bars and violence: illustrates flexibility of the method, changed study from one examining why bars were violent (even at violent bars, a low frequency behavior) to what situations led to violence
Bars • Young working class, two groups in an encounter where they are strangers • Crowded, no entertainment • High level of drunkenness (cheap drinks) • Over aggressive bouncers
