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Interrupted Time-Series Design
An interrupted time-series design is a quasi-experimental approach and a variant of the pretest-posttest design. In this methodology, a researcher takes a time series—multiple measurements of a dependent variable at regular intervals—both before and after a treatment is introduced. The treatment effectively 'interrupts' the ongoing measurements. Unlike the simpler pretest-posttest design, which relies on a single before-and-after measurement, the inclusion of multiple measurements allows researchers to better distinguish the actual effect of the intervention from normal variation.
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Research Methods in Psychology - 4th American Edition @ KPU
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Interrupted Time-Series Design
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Example of a One-Group Pretest-Posttest Design
Why is it difficult to conclude with certainty that a treatment was effective when using a one-group pretest-posttest design?
A researcher is using a one-group pretest-posttest design to study the effect of a new stress-reduction workshop on college students. Match each component of the study to its specific role in this research design.
A health psychologist wants to evaluate the impact of a weekend nature retreat on stress levels using a one-group pretest-posttest design. Arrange the steps of this study in the correct chronological order.
A researcher evaluates a new study-skills workshop using a one-group pretest-posttest design and observes a significant increase in students' grade point averages at the end of the semester. The researcher can definitively conclude that the workshop caused the increase because the pretest measurement successfully accounts for each participant's individual academic history.
Which of the following describes the basic procedure used in a one-group pretest-posttest design?
A researcher evaluates a new social-anxiety intervention using a one-group pretest-posttest design and finds that participants' anxiety levels are lower at the posttest than they were at the start. When appraising the scientific merit of the claim that 'the intervention caused the change,' a peer reviewer would note that the lack of a comparison group makes it impossible to rule out threats like maturation or history. Consequently, in terms of research design standards, this study is evaluated as having critically low _____ validity.
When using a one-group pretest-posttest design to evaluate a new mindfulness intervention, the researcher uses the pretest to establish a(n) _____ for participants' stress levels before the intervention occurs.
A researcher evaluates a new math tutoring software using a one-group pretest-posttest design. To control for potential order effects, the researcher can counterbalance the study by having half of the participants take the posttest exam before they use the tutoring software.
Analyze the structural differences between a within-subjects experiment and a one-group pretest-posttest design. Match each design characteristic to the research design or feature it describes.
An educational psychologist wants to evaluate the effectiveness of a new reading intervention using a one-group pretest-posttest design. Arrange the steps of the research process and the subsequent evaluation of its findings in the correct chronological and logical order.
Describe the key characteristics of a one-group pretest-posttest design and explain why the order of conditions cannot be counterbalanced in this specific design.
Based on the characteristics of a one-group pretest-posttest design, explain why the school psychologist's conclusion is difficult to make with certainty. What specific feature is missing from this study design that makes it vulnerable to alternative explanations?
A researcher wants to study the effect of a new anti-bullying curriculum using a one-group pretest-posttest design. Briefly describe the exact sequence of steps the researcher must take to measure the dependent variable (students' attitudes toward bullying) and administer the treatment according to this specific quasi-experimental design.
Time Series Analysis and Its Applications: With R Examples (Third edition)
Time Series learning
Interrupted Time-Series Design
Which of the following best describes the defining characteristic of a time series in psychological research?
Match each component of a time series design with its correct description in a psychological study context.
A clinical psychologist monitors a patient's self-reported anxiety levels every morning for three months to evaluate the stability of their symptoms during a new treatment. Because these quantitative measurements are taken at sequential intervals over a continuous period, the psychologist is using a(n) ________.
True or False: A psychologist who monitors a patient's self-reported anxiety () every morning for a year, but then collapses all those data points into a single annual mean () for their final report, is effectively performing a time series analysis.
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In the context of research methods, which of the following best defines a 'time series'?
Match each core component of a time-series design to its corresponding application in a study monitoring how student sleep quality changes throughout an academic year.
A researcher tracks the number of daily calls to a suicide prevention hotline for consecutive days to see if the frequency of calls increases during the winter holidays. True or False: This research approach is an example of a time series.
A researcher wants to use a time series approach to investigate weekly levels of test anxiety among first-year university students across one full academic semester. Arrange the following steps in the logical order required to correctly design and execute this time series study.
What is the primary purpose of utilizing a time series approach in psychological research?
A researcher monitors a group's average weekly mood ratings for an entire year to evaluate the impact of a new wellness program. Why is this time-series approach more informative than simply comparing one week of ratings before the program to one week after?
A researcher claims that a new school-wide mindfulness program significantly reduced student stress based on a single measurement taken two weeks after the program began. To evaluate whether this claim is justified or if the low stress levels are merely a temporary fluctuation, a critic would argue that the researcher should have used a(n) _____ to examine data at sequential intervals over a continuous period.
A school psychologist tracks the number of daily disciplinary incidents at a middle school for school days before and school days after implementing a new positive behavior intervention. This research design, which relies on a set of quantitative measurements taken at sequential intervals over a continuous period of time to track trends, is called a(n) _____.
An educational psychologist is analyzing a time-series plot of weekly student anxiety scores collected over an entire school year to evaluate the impact of a mid-semester stress-reduction workshop. To ensure the observed changes are truly due to the workshop, the researcher must rule out alternative explanations. Match each hypothetical pattern of time-series data to the specific threat to internal validity it represents.
A school district claims that its new anti-bullying curriculum is highly effective because the number of reported bullying incidents in the semester following the program's launch was lower than in the semester immediately preceding it. A research psychologist critiques this claim, arguing that the district should instead evaluate a continuous time series of monthly bullying incidents spanning three years before and three years after the launch.
Which of the following best explains why the psychologist's recommendation is a more valid way to evaluate the curriculum's effectiveness?
Learn After
Example of an Interrupted Time-Series Design: Factory Shift Reduction
Example of an Interrupted Time-Series Design: Student Absences
Interrupted Time-Series Design with Nonequivalent Groups
AB Design
Advantage of Interrupted Time-Series Over Pretest-Posttest Designs
Which of the following procedures is the defining characteristic of an interrupted time-series design?
In an interrupted time-series design, researchers rely on a single measurement before and a single measurement after a treatment to distinguish the actual effect of an intervention from normal variation.
A clinical psychologist wants to evaluate the impact of a new mindfulness-based stress reduction (MBSR) program on patients' anxiety levels using an interrupted time-series design. Arrange the following steps of the study in the correct chronological order.
Researchers using an interrupted time-series design must analyze data patterns to determine the internal validity of an intervention. Match each hypothetical data pattern with the analytical conclusion it most strongly supports.
You are designing a quasi-experimental study to determine if a new 'Mandatory Recess' policy (implemented on October 1st) improves elementary students' focus. To create an interrupted time-series design that distinguishes the policy's effect from the natural 'mid-semester slump' in student engagement, which of the following data collection schedules should you propose?
In an interrupted time-series design, measurements of a dependent variable are taken at regular intervals both before and after the treatment is introduced.
A researcher critiquing a study that relies on a single 'before-and-after' measurement argues that this method is insufficient to judge an intervention's success. To accurately evaluate whether an observed change reflects a genuine intervention effect rather than _____, the researcher recommends using an interrupted time-series design with multiple measurements before and after the treatment.
A team of psychologists wants to choose the correct methodology for different studies. Match each research scenario or description with the most appropriate design term based on the interrupted time-series methodology.
An investigator is analyzing the source of fluctuations in a study on workplace productivity. They note that a simple pretest-posttest design makes it difficult to separate treatment effects from normal variation. To better distinguish the actual effect of the intervention from normal variation, the researcher should use an interrupted time-series design to incorporate _____ measurements of the dependent variable before and after the treatment.
A research methods class is evaluating the validity of a proposed study on student absences. Arrange the steps below in the correct chronological order to properly execute an interrupted time-series design.
Define the interrupted time-series design and explain its structure as a variant of the pretest-posttest design. In your explanation, highlight the specific operational difference between this design and a simple pretest-posttest design, and state the main advantage this difference provides to researchers.
Based on the case context, justify the choice of research design by explaining why the psychologist's decision to collect multiple weekly measurements over a sixteen-week period is superior to using a simple before-and-after measurement. How does this methodology help in understanding the intervention's true impact?
A clinical director wants to apply an interrupted time-series design to evaluate whether a new scheduling app reduces client missed appointments. Write a brief explanation (1-3 sentences) detailing how the director should schedule their measurements of missed appointments relative to the introduction of the app.