key term - Within-Subjects Design

Definition

A within-subjects design, also known as a repeated-measures design, is an experimental design where the same participants are exposed to all the different conditions or treatments being studied. This means that each participant serves as their own control, allowing for a more direct comparison of the effects of the different conditions.

5 Must Know Facts For Your Next Test

1. Within-subjects designs allow for greater statistical power compared to between-subjects designs, as they reduce the influence of individual differences.
2. Repeated exposure to the same participants helps to control for extraneous variables and individual differences that could affect the dependent variable.
3. Counterbalancing is essential in within-subjects designs to mitigate potential order effects, where the order of the conditions may influence the results.
4. Within-subjects designs are particularly useful when the research question involves comparing the performance or responses of the same individuals under different conditions.
5. Potential drawbacks of within-subjects designs include practice effects, fatigue, and carry-over effects, which can be addressed through counterbalancing and appropriate data analysis techniques.

Review Questions

• Explain the key difference between a within-subjects design and a between-subjects design.
  • The key difference between a within-subjects design and a between-subjects design is that in a within-subjects design, the same participants are exposed to all the different conditions or treatments being studied, whereas in a between-subjects design, different participants are assigned to different experimental conditions. This means that in a within-subjects design, each participant serves as their own control, allowing for a more direct comparison of the effects of the different conditions, while in a between-subjects design, the responses of different groups are compared to determine the effect of the independent variable.
• Describe the role of counterbalancing in a within-subjects design and explain why it is important.
  • Counterbalancing is an essential technique used in within-subjects designs to control for order effects. Order effects refer to the potential influence that the order in which participants are exposed to the different conditions may have on the results. By systematically varying the order in which participants experience the conditions, counterbalancing helps to ensure that any observed differences in the dependent variable are due to the independent variable and not simply the order in which the conditions were presented. This is important because it helps to increase the internal validity of the study and allows for a more accurate assessment of the effects of the different conditions.
• Analyze the potential advantages and disadvantages of using a within-subjects design compared to a between-subjects design.
  • The primary advantage of a within-subjects design is the increased statistical power, as it reduces the influence of individual differences by having the same participants experience all the conditions. This allows for a more direct comparison of the effects of the different conditions. Additionally, within-subjects designs help to control for extraneous variables that could affect the dependent variable. However, potential drawbacks include practice effects, where participants may improve their performance over time, fatigue effects, and carry-over effects, where the experience in one condition may influence the performance in a subsequent condition. These potential issues can be addressed through counterbalancing and appropriate data analysis techniques. Ultimately, the choice between a within-subjects or between-subjects design depends on the research question, the nature of the study, and the tradeoffs between statistical power and potential confounding factors.

Related terms

Between-Subjects Design: In a between-subjects design, different participants are assigned to different experimental conditions, and the responses of these groups are compared to determine the effect of the independent variable.

Repeated Measures:

Repeated measures refers to the fact that the same participants are measured or observed under different conditions or at multiple time points, allowing for within-subject comparisons.

Counterbalancing: Counterbalancing is a technique used in within-subjects designs to control for order effects by systematically varying the order in which participants are exposed to the different conditions.