Google

A between-subjects design becomes strictly necessary when a within-subjects approach is difficult or impossible to carry out. This typically occurs in two main scenarios: first, when severe time constraints make it unfeasible to test each individual in all conditions; and second, when an experiment involves a treatment meant to produce long-term behavioral changes. In the latter case, a successful initial treatment permanently alters the participants, making them unsuitable for subsequent testing in a control condition.

Situations Requiring a Between-Subjects Design

A classic situation necessitating a between-subjects design due to severe time constraints is testing participants in an opportunistic field setting, such as a doctor’s waiting room or a grocery store line. In these scenarios, researchers typically do not have enough time to test each participant across all experimental conditions, forcing them to assign each person to only a single condition.

Example of Time Constraints in Between-Subjects Designs

Research aimed at creating enduring behavioral changes requires a between-subjects design because participants cannot return to their original baseline state after treatment. For example, in a study testing the effectiveness of psychotherapy or attempting to reduce prejudice through cross-racial interaction, successful treatments permanently alter the participants. Consequently, they can no longer serve in a subsequent control condition, making a within-subjects design impossible.

Learn Before

Related