Which type of design involves observing behaviors before treatment, during treatment, after treatment is removed, and when treatment is continued?

Reversal design is characterized by its systematic measurement of behaviors across several phases, allowing for a clear observation of how treatment affects those behaviors. In this design, practitioners may observe the target behaviors before treatment begins, during treatment, after the treatment is removed, and then again when treatment is reinstated. This approach provides valuable insight into the effectiveness and impact of the treatment, as it demonstrates the changes in behavior in relation to the presence or absence of the intervention.

This design is particularly effective in evaluating the functionality of a specific treatment, as it illustrates not only the initial effects of the intervention but also allows for a clear comparison when the treatment is withdrawn. This helps to establish a cause-and-effect relationship between the treatment provided and the behavior observed.

In contrast, experimental design typically involves controlled conditions to test the effects of one or more variables, often lacking the repeated measures characteristic of reversal designs. Longitudinal design tracks changes across different time points but does not necessarily involve the systematic removal of treatment, while cross-sectional design collects data at one point in time, making it unsuitable for observing changes associated with treatment interventions over multiple phases. Therefore, the comprehensive nature of reversal design in assessing treatment effects makes it the correct choice for this scenario.