Strengths of Switching Replication

Which of the following best describes the specific threat to internal validity known as differential history?

In a research study comparing two different schools, if an unexpected event like a localized flu outbreak affects only one of the schools during the study, this situation constitutes a threat known as differential history.

A researcher is evaluating a new mindfulness-based stress reduction program by comparing two different nursing homes. Nursing Home A receives the program, while Nursing Home B serves as the control. During the study, Nursing Home A unexpectedly undergoes a noisy, two-week-long roof renovation that does not occur at Nursing Home B. Because this extraneous event affected only one of the groups, it creates an internal validity threat known as ________ ________.

A researcher evaluates a new social-skills program by comparing two different schools in a nonequivalent groups design. Match each occurrence during the study to its correct classification within the analysis of internal validity.

A researcher is evaluating a study that compares two separate nursing homes ($Nursing Home A$ and $Nursing Home B$) to test a new physical activity program. Residents were already living in these homes and were not randomly assigned to groups. Rank these extraneous events from the least severe to the most severe threat to internal validity regarding differential history.

In a nonequivalent groups design, differential history is a threat to internal validity that occurs when an extraneous event affects both the treatment and control groups in the same way.

In a pretest-posttest nonequivalent groups design, why is the study still vulnerable to 'differential history' even though the design helps account for general 'history' effects?

A researcher is reviewing four studies that each used a nonequivalent groups design with a pretest and posttest. Match each scenario to the internal validity threat it most directly illustrates.

A researcher uses a pretest-posttest nonequivalent groups design to examine whether a financial-literacy workshop reduces impulsive spending at two different community colleges. College A receives the workshop (treatment); College B does not (control). Midway through the study, College A's student government independently launches a campus-wide budgeting challenge with cash prizes, while College B's campus has no comparable initiative. When the posttest shows lower impulsive-spending scores at College A, a peer reviewer argues that the result cannot be confidently attributed to the workshop alone.

The peer reviewer's concern is best described as _____, because an extraneous event that occurred at only one site during the study could independently account for the observed group difference even though the design already controls for events that affect both groups equally.

A colleague shares a preprint of a pretest-posttest nonequivalent groups study comparing an anxiety-reduction program offered at one community health clinic (treatment) versus another clinic in a nearby town (control). You are asked to evaluate whether differential history is a credible threat to the study's internal validity. Arrange the following steps in the most logical order for conducting that evaluation.

Define the term 'differential history' as a threat to internal validity. In your answer, identify the research design in which it arises, explain how it differs from a general history effect, and state how it impacts a researcher's ability to draw conclusions about a treatment.

Using the scenario provided, diagnose the threat to internal validity that is present. Explain why the pretest-posttest design failed to protect against this threat in this scenario, and justify why the researchers cannot conclude that the mindfulness program caused any observed differences in posttest scores.

A researcher is using a nonequivalent groups design to compare a new coaching intervention at two schools. During the study, a student drug overdose occurs at the treatment school but not the control school. Apply the concept of differential history to describe the specific impact of this event on the study's posttest scores and internal validity.