Which of the following study designs can best determine the effect of promotional techniques on cafeteria sales?

An experimental study design is the best choice for determining the effect of promotional techniques on cafeteria sales because it allows researchers to manipulate specific variables—namely, the promotional techniques—while controlling for other factors that could influence the outcome. In an experimental design, participants can be randomly assigned to either a treatment group, which is exposed to the promotional techniques, or a control group, which is not. This setup helps to establish a cause-and-effect relationship by isolating the impact of the promotional techniques on sales.

The strength of this design lies in its ability to provide strong evidence regarding the effectiveness of the promotional techniques, as any significant differences in sales can be attributed to the interventions implemented, rather than external influences. In contrast, other study designs such as observational studies primarily focus on observing and documenting behaviors without manipulation, making it difficult to draw definitive conclusions about causality. Surveys gather self-reported data, which may not accurately capture the actual sales performance, and segmentation typically involves dividing a market into distinct groups but does not directly measure the impact of specific interventions.