Between-Subjects Design

A between-subjects design is an experimental research design in which each participant is assigned to only one condition, and the conditions are compared across different groups of people. It contrasts with within-subjects (repeated-measures) designs, in which every participant experiences every condition. Between-subjects designs avoid carry-over, learning, and fatigue effects from repeated exposure, but typically need larger samples to detect a given effect. In accessibility and HCI research, between-subjects designs are common when conditions cannot reasonably be re-experienced (e.g., a one-shot VR walkthrough, a first-impression usability test) or when prior exposure to one condition would bias responses to another.