Examination for Professional Practice of Psychology (EPPP) Practice Test

A researcher wants to investigate the effects of a brief treatment on 10 therapy clients. This research design is known as what?

1. Multiple baseline

2. ABAB

3. Interrupted time-series design

4. Nonequivalent control group

The correct answer is: Interrupted time-series design

The correct answer pertains to a methodology that allows researchers to assess the effects of an intervention over time, particularly within a single group of subjects. In an interrupted time-series design, the researcher collects data at multiple time points before and after the introduction of the treatment. This allows for a robust analysis of changes attributable to the treatment, as it considers potential trends and fluctuations that naturally occur over time. In the context of studying the effects of a brief treatment on therapy clients, this design is advantageous because it enables the researcher to look for patterns or shifts in behavior or symptoms that align with the timing of the intervention. By demonstrating changes that happen following the treatment's implementation, the researcher can better infer whether the treatment had a noticeable impact. Other designs, like the ABAB design, involve alternating phases of treatment and no treatment within the same individual to assess the effects more directly. However, this particular scenario describes a setup more akin to the interrupted time-series approach rather than a repeated measure framework. Therefore, the characteristics of the research design fit best with interrupted time-series, making it the most suitable choice.