Regression to the Mean as a Threat to Internal Validity
Regression to the mean acts as a severe threat to internal validity when participants are selected for a research study specifically because of their extreme initial scores. Statistically, individuals who achieve exceptionally high or low scores on a pretest are highly likely to score closer to the population average on a subsequent posttest simply due to natural, random variability. This makes it incredibly difficult to determine whether a shift in scores was genuinely caused by the experimental treatment or was merely the result of statistical regression.
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Research Methods in Psychology - 4th American Edition @ KPU
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Regression to the Mean as a Threat to Internal Validity
Which of the following best describes the statistical phenomenon of regression to the mean?
A researcher notices that participants who scored extremely high on anxiety before a stress-reduction workshop scored notably lower after it. She concludes the workshop genuinely reduced their anxiety. This conclusion is fully justified because any improvement following an extreme initial score must reflect a real treatment effect.
A researcher is studying test anxiety in a group of students. After an initial assessment, she categorizes three participants based on their scores relative to the group average. Match each participant's initial score with their most likely outcome on a follow-up test (assuming no intervention occurred) based on the phenomenon of regression to the mean.
In a clinical study on depression, researchers recruit a 'high-severity' group consisting of participants who scored in the top 5% on a baseline diagnostic scale. At a follow-up assessment, the group's average score improved, even for those who received no treatment. Arrange the logical steps that explain this outcome using the phenomenon of regression to the mean.
Under the statistical phenomenon of regression to the mean, if an individual's score on a random variable is extremely far from the average on the first measurement, what is the most likely outcome on a subsequent measurement?
According to the phenomenon of regression to the mean, if the first sample of a random variable is extremely below the average, the second sample is typically expected to be even further below the average.
A researcher claims that a new focus-enhancing technique is effective because participants who scored in the bottom on a baseline concentration task showed significant improvement after the intervention. To evaluate the scientific validity of this claim, a critic would point out that the improvement may not be due to the technique itself, but rather to the statistical tendency for extreme scores to naturally shift toward the average on retesting — a phenomenon known as _____.
A researcher measures a single random variable across two timepoints. Match each participant's initial score description with the expected direction of their second score under the phenomenon of regression to the mean.
A researcher notes that an extreme score on a baseline test appears much closer to the average upon a subsequent test. From a design perspective, regression to the mean is a statistical phenomenon that occurs when resampling a single _____.
Order the steps a researcher takes to evaluate whether regression to the mean has occurred when analyzing test scores across two time points.
Interrupted Time-Series Design
Control Group in Pretest-Posttest Designs
History as a Threat to Internal Validity
Maturation as a Threat to Internal Validity
Testing as a Threat to Internal Validity
Instrumentation as a Threat to Internal Validity
Regression to the Mean as a Threat to Internal Validity
Spontaneous Remission
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.
Learn After
Control Group in Pretest-Posttest Designs
Example of Regression to the Mean
In a research study, what condition primarily makes regression to the mean a severe threat to internal validity?
If a researcher specifically selects participants for an intervention because they scored in the extreme bottom 5% on a pretest, any subsequent improvement on their posttest scores can be confidently attributed solely to the effectiveness of the intervention.
A researcher is studying the impact of a new intensive reading program. Arrange the following steps in the correct order to illustrate how 'regression to the mean' acts as a severe threat to the internal validity of this study.
An educational researcher identifies the 30 students with the highest math-anxiety scores in a school and has them practice mindfulness for one week. On the posttest, their average anxiety scores have dropped significantly. Match each component of this research scenario to the specific role it plays in creating a threat to internal validity.
As a lead researcher, you are tasked with designing a new study to test an intervention for individuals experiencing extreme bouts of insomnia. To ensure the final results are not confounded by regression to the mean, arrange the following procedural steps in the order required to construct a valid experimental design.
According to the principle of regression to the mean, if participants are selected for a study specifically because they achieved exceptionally high pretest scores, what is the most likely statistical outcome for their posttest scores?
A researcher concludes that a new study-skills workshop is successful because the students who scored in the bottom on the first quiz showed a significant improvement on the second quiz. To evaluate the internal validity of this conclusion, one must account for the fact that these extreme scores were statistically likely to move closer to the group average due to _____ to the mean.
A researcher measures depressive symptoms in college students and recruits only the top most depressed students to participate in a new mindfulness intervention. At the end of the semester, the students' depressive symptoms decrease. In this design, regression to the mean is a major threat to internal validity because these participants were selected based on their extreme initial scores.
Match the pretest score scenario with its corresponding posttest tendency or statistical explanation under the threat of regression to the mean.
A clinical psychologist evaluates a new therapy for anxiety. She selects the patients with the highest anxiety scores from a clinic. After ten sessions of therapy, their anxiety scores decrease significantly. To evaluate the internal validity of this study, we must recognize that because participants were chosen for their extreme scores, the improvement is confounded by statistical _____.