If the subjects are only tested once, this is called a Between-Subjects Design.

Advantages of Between-Subjects Designs

• Includes a control or comparison group that helps to control for many extraneous variables.
• Can randomly assign participants to groups, which helps to balance extraneous variables across the groups.

Disadvantages of Between-Subjects Designs

• You can’t always randomly assign participants to groups.
• Large individual differences between participants may make it difficult to observe meaningful group differences.