Teaching Fractions Example of a Pretest-Posttest Nonequivalent Groups Design

Random Assignment in Pretest-Posttest Designs

Anti-Drug Program Example of a Pretest-Posttest Nonequivalent Groups Design

Differential History

Pretest-Posttest Design with Switching Replication

In a pretest-posttest nonequivalent groups design, how are the groups structured and assessed to evaluate the effect of an intervention?

A researcher is evaluating a new mindfulness program in two different schools using a pretest-posttest nonequivalent groups design. Match each component of the study with the logical function it serves in this design.

A researcher evaluates a new study-skills workshop by measuring the GPA of two existing student clubs in September and again in December. Only one club attends the workshop. If both clubs show a GPA increase, but the workshop club's increase is significantly greater, the researcher can use the non-workshop club's data to argue that the improvement was not caused simply by students becoming more acclimated to the semester over time.

Arrange the research steps of a pretest-posttest nonequivalent groups design in the correct order required to logically isolate a treatment effect from natural maturation.

In a pretest-posttest nonequivalent groups design, both the treatment group and the nonequivalent control group complete an initial baseline measurement before the intervention occurs.

In a study using a pretest-posttest nonequivalent groups design, why is it specifically useful to compare the pretest-to-posttest change in the treatment group against the pretest-to-posttest change in the control group?

A researcher using a pretest-posttest nonequivalent groups design finds that both the treatment group and the control group improved their scores by exactly 15 points. In evaluating these results, the researcher should _____ the conclusion that the treatment was uniquely responsible for the observed improvement.

Imagine you are a school psychologist tasked with evaluating a new reading intervention program across two different elementary schools. You cannot randomly assign students to the program. Describe how you would set up a pretest-posttest nonequivalent groups design to evaluate this intervention, specifying your groups, measurements, and why this design improves upon a posttest-only approach.

Based on the case context, analyze how Dr. Rivera should interpret the results of her pretest-posttest nonequivalent groups design to determine if the wellness program was effective. What specific comparison must she make, and why does the decrease in both groups not necessarily invalidate the program's effectiveness?

A researcher argues that randomly assigning participants is the only valid way to evaluate an intervention. Using the principles of a pretest-posttest nonequivalent groups design, evaluate this claim. In one to three sentences, explain how this quasi-experimental design provides a strong alternative when random assignment is not possible.

A clinical psychologist wants to test the effectiveness of a new cognitive-behavioral therapy (CBT) mobile app for reducing anxiety. She implements a pretest-posttest nonequivalent groups design by recruiting participants from two existing outpatient clinics: Clinic A (where patients use the app) and Clinic B (where patients receive standard care without the app). Both clinics measure anxiety levels at the start of the study (pretest) and six weeks later (posttest).

Which of the following outcomes would provide the strongest evidence that the app caused a reduction in anxiety, while accounting for potential maturation effects?

A developmental psychologist evaluates a new reading intervention across two different schools using a pretest-posttest nonequivalent groups design. Match each hypothetical pattern of results (from pretest to posttest) with the most accurate analytical interpretation of what the pattern indicates about the treatment's effectiveness or potential threats to internal validity.

A clinical psychology researcher uses a pretest-posttest nonequivalent groups design to evaluate a new mindfulness app. Clinic A (treatment group) and Clinic B (nonequivalent control group) are measured on stress levels at baseline (pretest) and after six weeks (posttest).

Results:

• Clinic A (App): Pretest Mean = $45$, Posttest Mean = $25$ (reduction of $20$ points)
• Clinic B (Control): Pretest Mean = $30$, Posttest Mean = $25$ (reduction of $5$ points)

Evaluate the following three interpretations of these results. Arrange them in order from the MOST methodologically sound (Order 1) to the LEAST methodologically sound (Order 3).