Example of a Posttest Only Nonequivalent Groups Design

Pretest-Posttest Nonequivalent Groups Design

Controlling Confounds in a Posttest Only Nonequivalent Groups Design

Which of the following best describes a posttest only nonequivalent groups design?

In a posttest only nonequivalent groups design, researchers can confidently assume that the treatment caused any observed differences in the final outcomes.

A mental health researcher evaluates a new depression treatment by applying it to all patients at Clinic A and comparing them to patients at Clinic B who received standard care. Patients were not randomly assigned to the clinics. After six weeks, the researcher measures depression levels in both groups and expresses concern that Clinic A patients may have had higher baseline symptom severity than those at Clinic B. Match each element of this study to its corresponding role in the described research design.

A psychologist evaluates a new classroom intervention by applying it to one school and comparing the students' final test scores to those of a nearby school that did not use the intervention. No initial testing was conducted. Arrange the following steps in the logical sequence a researcher would use to analyze why this study fails to establish a clear cause-and-effect relationship.

A university researcher is tasked with planning a study to evaluate a new 'Mindfulness-Based Stress Reduction' (MBSR) elective for undergraduate students. The university administration allows the course to be offered to students in the Nursing program, while students in the Social Work program will not have access to it. However, the administration prohibits any baseline stress testing before the semester begins and forbids the random assignment of students between the two programs. Which of the following research plans correctly constructs a posttest only nonequivalent groups design to evaluate this intervention?

Match each component of the posttest only nonequivalent groups design with its correct description based on the concept definition.

A researcher evaluates a new mindfulness program by implementing it in one high school and comparing the students' final stress scores to those of a neighboring high school that did not use the program. If the researcher asserts that the program 'caused' the lower stress scores in the first school, a critical evaluator would reject this claim because the design fails to rule out the influence of _____.

A school psychologist compares the final exam reading scores of an existing third-grade class that received a new vocabulary curriculum with another existing third-grade class that did not. Because the classes are intact groups and students were not randomly assigned to them, this study is an application of a posttest only nonequivalent groups design.

In a posttest only nonequivalent groups design, the lack of random assignment when allocating participants means that any observed posttest differences may be caused by the treatment, but they could equally be the result of pre-existing _____ variables.

Order the steps involved in executing and evaluating a study using a posttest only nonequivalent groups design, from the initial setup to the final evaluation of internal validity.