Quasi-Experimental Research Design Overview

In which circumstance is a quasi-experimental research design most likely chosen?

When doing research in an applied or natural setting where control is difficult to impose.

What is the most common reason for using quasi-experimental research designs?

Participants cannot be randomly assigned to groups.

What can be inferred from quasi-experimental designs despite lacking controls?

Causal inferences can be made to the extent that rival hypotheses can be ruled out.

What distinguishes quasi-experimental designs from strong experimental designs?

A lack of control of extraneous variables.

When should a researcher consider using quasi-experimental designs?

When they cannot randomly assign participants to groups.

How can rival hypotheses be ruled out in quasi-experimental designs?

By making a complex prediction.

What can enhance the ability to determine the effectiveness of an anti-smoking campaign in a quasi-experimental study?

Identify a similar school that is not using the campaign and include them in a nonequivalent comparison group design.

What is a possible rival hypothesis in a quasi-experimental study with a control group affected by a fire?

There was a differential history or selection-history effect.

What was the city's action to reduce gasoline use in 2005?

Imposed a $2.50 per gallon tax on gasoline.

What type of study design involves analyzing data from before and after a specific intervention, such as a tax?

Interrupted time-series design.

Which design is threatened by selection bias due to the lack of random assignment?

Nonequivalent comparison group design.

What internal validity threat is associated with the interrupted time-series design?

History.

What does the nonequivalent comparison-group design lack that affects its validity?

Random assignment of participants to the groups.

What is an example of an additive/interaction threat in a nonequivalent comparison-group design?

Selection-maturation.

What is the major interpretational difficulty of the non-equivalent comparison group design?

Being sure that any differences between groups at the end of the experiment result from the independent variable's influence alone.

What distinguishes the nonequivalent comparison group design from the pretest-posttest control group design?

Random assignment of participants to groups.

Which design is considered the best for eliminating potential confounds?

Pretest-posttest control-group design.

What effect occurs when the control group experiences an event that affects their performance, such as going on rides before testing?

Selection-history effect.

In which quasi-experimental design is the selection-history effect particularly problematic?

Non-equivalent comparison group.

What might it indicate if the experimental group scores higher than the control group at the start and only the experimental group's scores increase?

It could reflect an influence of the independent variable, but also other confounding factors.

What is a threat to internal validity that occurs when participants in one group become more experienced or fatigued than those in another group?

Selection-maturation.

What is the primary concern with the interrupted time-series design regarding external events?

The history effect can confound results.

What type of design does not manipulate the independent variable but still allows for comparison between groups?

Nonequivalent comparison group design.

What is a potential outcome of the nonequivalent comparison group design if pre-existing differences exist?

Differences in outcomes may not be solely due to the independent variable.

What is the role of pretesting in the pretest-posttest control group design?

It allows for comparison of scores before and after the intervention.

What is the main purpose of using a control group in experimental designs?

To isolate the effect of the independent variable.

How does selection bias affect the validity of research findings?

It can lead to inaccurate conclusions about the effects of the independent variable.

What is the significance of random assignment in experimental designs?

It helps ensure that groups are equivalent at the start of the experiment.

What is the impact of selection-attrition on study results?

It can skew results if participants drop out at different rates between groups.

What does the term 'regression artifact' refer to in research design?

It refers to the tendency for extreme scores to move closer to the mean upon retesting.

What is a strategy for dealing with preexisting differences between experimental and control groups in the nonequivalent comparison group design?

Matching participants.

How effective is matching participants compared to random assignment in experimental designs?

Matching is as effective as randomly assigning participants from the start.

What confounding factor can be introduced when matching participants based on extreme scores?

Regression-artifact phenomenon.

What is a possible outcome of the nonequivalent comparison group design when both groups improve on the posttest?

It could reflect that the independent variable had an effect on the experimental group or a selection-maturation effect.

What does it indicate if the control group scores higher than the experimental group on both pretest and posttest, but the experimental group shows more improvement?

It may indicate a regression-artifact effect if the experimental group was selected for their low initial scores.

In the context of Dr. Shanz's strength training experiment, what type of effect is observed when the experimental class shows significant improvement despite starting weaker?

Crossover effect.

What rival hypothesis can the presence of a crossover effect usually rule out?

Regression-artifact.

What must Dr. Kaiser consider when assessing the effectiveness of the aerobic program for girls?

Whether there was a selection-maturation effect.

What is the most common dependent variable used in the nonequivalent comparison group design?

Latency measure.

What is a selection-maturation effect in experimental design?

It refers to changes in participants that occur over time, which can confound results.

What is the significance of an unreliable dependent measure in experimental outcomes?

It can lead to incorrect conclusions about the effects of the independent variable.

What could a participant-expectation effect imply in an experimental study?

Participants' expectations about the treatment can influence their responses.

What does the term 'local history' refer to in the context of experimental design?

Events that occur outside the experiment that can affect the results.

How can the independent variable affect the outcomes in a nonequivalent comparison group design?

It can lead to different degrees of improvement between experimental and control groups.

What is the implication of a significant increase in strength in the experimental group compared to the control group?

It suggests that the experimental method may have been effective.

What does 'attrition effect' mean in experimental research?

It refers to participants dropping out of the study, which can bias results.

What is the purpose of using a pretest in experimental designs?

To establish a baseline for comparison with posttest results.

What is a common challenge when interpreting results from quasi-experimental designs?

The presence of confounding variables that may affect the outcomes.

What does 'intragroup regression' refer to in experimental design?

It describes the tendency of extreme scores to move closer to the mean on subsequent tests.

What is the role of the control group in an experimental study?

To provide a baseline for comparison against the experimental group.

Why is it important to consider age when selecting participants for an experiment?

Age can influence the outcomes and effects of the independent variable.

What is a common method to measure latency in research?

Difference or change scores from posttest minus pretest.

Which of the following is NOT a bias in nonequivalent comparison group designs?

Testing bias.

What must be true for making a causal inference from quasi-experimental evidence?

The suspected cause must covary with the effect, precede the effect, and rival hypotheses must be ruled out.

In a nonequivalent comparison group study, what is the typical sequence of events for the experimental group?

The experimental group gets a pretest, then the experimental treatment, then a posttest.

What is a selection-history confound in a study comparing two nonequivalent groups?

An event intervenes between pretest and posttest and affects just one of the groups.

Which threat to internal validity is most likely a problem in nonequivalent comparison group designs?

Selection bias.

In the hypothetical study assessing the effectiveness of the 'Just Say No' campaign, what threat to internal validity is present?

Selection-history.

What can Dr. Hunter do to minimize pre-test differences in her nonequivalent comparison group design?

Match participants in variables closely related to the independent variable.

How can internal validity be increased in a nonequivalent comparison group design?

By not allowing students to self-select into groups.

In which design is differential dropout rates most likely a problem?

Nonequivalent comparison group.

The ___________ is to ___________ as nonequivalent comparison group design is to posttest-only design with nonequivalent groups.

Interrupted time series design is to one group pretest-posttest design.

Why might researchers choose a time-series design over a traditional two-group experimental design?

It can be difficult to find a sufficiently comparable control group.

What are the three key requirements for a causal inference in quasi-experimental research?

Covariation of cause and effect, temporal precedence, and ruling out rival hypotheses.

What is the role of pretests in nonequivalent comparison group designs?

They help establish baseline measurements before treatment.

What does selection-attrition bias refer to in research designs?

Differential dropout rates between experimental and control groups.

What is a potential issue with self-selection in research groups?

It can lead to biased results due to non-random assignment.

What is the effect of a historical event on a nonequivalent comparison group study?

It may influence outcomes differently across groups, complicating interpretation.

What is the significance of matching participants in research?

It helps control for pre-existing differences related to the independent variable.

What is a common characteristic of quasi-experimental designs?

They lack random assignment to groups.

What is the purpose of using a posttest-only design with nonequivalent groups?

To evaluate the effect of an intervention without pretest biases.

What does the term 'selection-regression bias' refer to?

It occurs when groups differ in their baseline characteristics, affecting outcomes.

What is the importance of ruling out rival hypotheses in causal inference?

It strengthens the validity of the causal relationship being examined.

What is a quasi-experimental design involving multiple measures of the dependent variable on a single group, both before and after treatment?

One group pretest-posttest design.

What is a strong experimental design involving multiple measures of the dependent variable on a single group, both before and after treatment?

Interrupted time series.

What experimental design uses multiple dependent measures on the experimental group, then takes measures on control participants over time?

Non-equivalent control group.

What design staggers the time of presentation of the independent variable across participants?

Multiple baseline design.

What experimental design did Dr. Toris use to test an incentive program for attendance?

Interrupted time series.

What is typically visual inspected in an interrupted time series design?

The pre- and post-treatment pattern of dependent measure scores.

What is the most likely source of confounding in an interrupted time-series design?

History.

How does one determine whether the independent variable had an effect in an interrupted time-series design?

By looking for changes in the response pattern from pre- to post-treatment.

What design involves taking multiple measures on the dependent variable both before and after treatment?

Interrupted time series.

What does the 'interruption' refer to in an interrupted time series design?

The introduction of the independent variable.

What type of design is used when a small town measures cell phone use among drivers before and after banning texting while driving?

Interrupted time series design.

What research design could best test the effectiveness of the National Science Foundation's grant program for young scientists?

Regression-discontinuity design.

What is the purpose of the National Science Foundation's grant program?

To support young scientists based on their publication output.

What does the term 'attrition' refer to in the context of experimental design?

The loss of participants over time.

What is a key characteristic of a non-equivalent control group design?

It compares groups that are not randomly assigned.

What is the primary focus of a regression-discontinuity design?

To evaluate the effect of an intervention at a cutoff point.

What is the main advantage of using a before-after design?

It allows for direct comparison of measures before and after treatment.

What is a potential limitation of using a single group in experimental designs?

It may lead to confounding variables affecting the results.

What is the difference between a posttest-only design and a pretest-posttest design?

A pretest-posttest design includes measurements before and after treatment, while posttest-only does not.

What is the significance of multiple observations in a study design?

They enhance the reliability of the findings by allowing for trend analysis.

What does 'participant expectations' refer to in the context of extraneous variables?

The influence of participants' beliefs about the study on their behavior.

What is the role of instrumentation failure in experimental designs?

It can introduce errors in data collection, affecting the validity of results.

What is NOT a requirement of the regression-discontinuity design?

The cutoff score should be located at one of the extreme ends of the distribution.

How can you tell if your treatment had an effect in a regression-discontinuity design?

By determining if there is a discontinuity in the regression line for the people above and below the cutoff score.

What is the primary threat to internal validity in a regression-discontinuity study?

Selection-history.

What type of experimental design was used in Vaughn et al. (2009) study with poor readers?

Regression discontinuity.

Which of the following is NOT a quasi-experimental design?

Pretest-posttest control group design.