Question

Favoring within-subjects: The effect is small (relative to the noise) - i.e., it's a low-power situation; when the experiment is very brief; when the subjects are very heterogeneous (and, therefore, failures of random assignment are more likely and more dangerous)

Answer 1

The question addresses the considerations in choosing a within-subjects design in psychological experiments, especially when facing low power and participant heterogeneity.

Step-by-step explanation:

The question pertains to the design of a psychological experiment and the considerations for choosing within-subjects design, specifically in situations where there is a low power to detect small effects among a very heterogeneous group of participants. To mitigate the influence of experimenter bias and lurking variables, it is crucial to employ strategies such as random assignment and blind procedures. It highlights the importance of random assignment and single-blind study to control for bias and lurking variables, while also noting the ethical and sampling constraints faced by researchers.

Random assignment is essential to ensure that there are no systematic differences between treatment groups prior to the introduction of the independent variable. Additionally, using a single-blind study where participants are unaware of their group assignments can help prevent their expectations from influencing the results. However, researchers are often faced with ethical and practical limitations, such as when dealing with unethical study designs or small sample sizes, that can restrict their methodological choices.