Random Assignment

Advantages of Between-Subjects Experiments

Independent-Samples t-Test

One-Way ANOVA

Within-Subjects Experiment

Matched-Groups Design

Examples of Between-Subjects Experiments

Example of Lack of Context in Between-Subjects Designs

Combining Between-Subjects and Within-Subjects Designs

Equivalent Groups

Nonequivalent Groups

Which of the following best describes a between-subjects experiment?

In a between-subjects experiment, researchers test each participant across every level of the independent variable to directly compare their individual responses.

A researcher is conducting a between-subjects experiment to test if '8 hours of sleep' versus '4 hours of sleep' affects cognitive performance on a memory task. Arrange the steps of this specific study in the correct chronological order.

A researcher investigates whether a new font improves reading speed. They assign 50 participants to read a text in 'Times New Roman' and another 50 participants to read the same text in 'OpenDyslexic'. Match each aspect of this study to the structural logic of a between-subjects experiment.

You are tasked with creating a research protocol to investigate whether a 'Gamified' exercise app increases user motivation more than a 'Standard' exercise app. To avoid 'carryover effects'—where the experience with one version of the app might influence the user's perception or performance with the other—you decide to implement a between-subjects experiment. Which of the following plans should you develop to successfully fulfill this design requirement?

A researcher is evaluating whether to use a within-subjects or a between-subjects design for a study on a permanent educational intervention. They determine that a(n) _____ design is the only valid choice because the intervention results in an irreversible change, making it impossible for the same participants to serve in both the experimental and control conditions.

An experimental design in which each participant is exposed to only a single level of the independent variable is called a(n) _____ experiment.

A clinical researcher measures each participant's stress level at three time points: before a mindfulness program begins (Week 0), after four weeks of training (Week 4), and after eight weeks of training (Week 8). Every participant completes the same single program. The researcher argues that this is a between-subjects design because each participant is assigned to only one program. This argument is correct.

A researcher studies whether type of reward (monetary payment, verbal praise, or no reward) affects how long elementary school children persist on a difficult puzzle. One group receives money after each puzzle attempt, a second group receives verbal praise, and a third receives nothing. No child participates in more than one condition. Match each term to the description that correctly identifies its role in this study.

A research team wants to test whether a new anti-anxiety drug (Drug A), an established drug (Drug B), or a placebo reduces self-reported anxiety in adults with generalized anxiety disorder. They must design the study and analyze the data responsibly. Arrange the following decisions and actions in the order that best reflects sound research practice for a between-subjects experiment.

Define a between-subjects experiment. In your definition, clarify how participant exposure to the independent variable distinguishes this design from a within-subjects design.

Explain why this study is classified as a between-subjects design. Additionally, explain how stable individual differences among the participants in the separate groups affect the within-groups variability ($MS_W$) and the resulting $F$ statistic in the One-Way ANOVA.

Suppose you are designing a between-subjects experiment to test the effects of two different teaching methods on student learning. What must you do when assigning participants to the two conditions, and what is the primary methodological reason for doing so regarding participant variables?