Overview

In a one-way within-subjects design, sometimes referred to as a repeated-measures design, each case is measured on or contributes a data point to every level of the independent variable. Because of this, subjects function in the design as their own controls; this in turn enhances the power of the statistical design. If the drawbacks to this design can be overcome (e.g., carry-over effects; see Gamst et al., 2008), it often becomes the design of choice for a one-way design.

Numerical example

The Automobile Manufacturers Association wished to study the effects of alcohol consumption on driving different types of vehicles. This hypothetical study called for drivers to consume the equivalent of three alcoholic drinks and then drive a complex prescribed closed-track course in one of four kinds of vehicles. Because of the considerable individual differences in drinking and driving that were expected, and because it was believed that the carry-over effects from the different conditions could be largely negated by knowledge of the track, this was designed as a within-subjects study. The organization recruited 14 college students from a local university who were 21 years of age and familiarized them with the track layout. Students were then scheduled for 4 days over the next 2 weeks to drive the course. On each test day, each student was to drive a different vehicle (determined randomly for each student) around the course.