91Ó°ÊÓ

Researchers at the University of Houston decided to test the hypothesis that restaurant servers who squat to the level of their customers would receive a larger tip ("Effect of Server Posture on Restaurant Tipping," Joumal of \(A p\) plied Social Psychology [1993]: \(678-685\) ). In the experiment, the waiter would flip a coin to determine whether he would stand or squat next to the table. The waiter would record the amount of the bill and of the tip and whether he stood or squatted. a. Describe the treatments and the response variable. b. Discuss possible extraneous factors and how they could be controlled. c. Discuss whether blocking would be necessary. d. Identify possible confounding variables. e. Discuss the role of randomization in this experiment.

Step by step solution

01

Identify Treatments and Response Variable

The two treatments in this experiment are the standing posture vs. squatting posture by the restaurant server. The response variable is the tip received by the server.

02

Examine Extraneous Factors

Possible extraneous factors could include the size of the customer's bill, the customer's mood, time of day, and the server's overall service. They could be controlled by keeping the conditions uniform across all experiential trials, like the same serving timing and similar nature of service.

03

Discuss Necessity of Blocking

Blocking would not inherently be necessary in this experiment unless there are extraneous factors that can's be controlled and might cause a significant systemic difference in the treatments.

04

Identify Confounding Variables

Confounding variables could be any characteristics/conditions that vary with the posture variable and could affect the tips, such as server's personability, quality of service, or if the server is recognized by the customers.

05

Discuss Role of Randomization

Randomization, like flipping a coin to decide server's posture, protects against the influences of confounding variables. It helps in achieving more objective and accurate results by ensuring that each treatment is equally probable.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Response Variable

In this experiment, the primary outcome being measured is the amount of tip received by the server. This is known as the response variable. It is the variable that researchers are interested in understanding and analyzing to determine the effect of the server's posture on the tipping behavior of customers. By changing the server’s posture and observing changes in the tip amount, researchers can draw conclusions about causality. In this context, tips measure customer satisfaction or generosity, affected by the server's action.

Extraneous Factors

Extraneous factors are those variables that might influence the response variable but are not the primary focus of the experiment. In this study, some examples could be customer's mood, the time of day, or the bill's size. These factors might affect the generosity of the tip, irrespective of the server's posture.
To minimize their impact, keeping consistent conditions throughout the experiment is crucial:

• Ensure similar levels of service quality.
• Conduct experiments at similar times.
• Try to maintain a neutral atmosphere.

By controlling these factors, researchers aim to isolate the effect of the server’s standing or squatting.

Confounding Variables

Confounding variables are those that are intertwined with both the response variable and the treatment, making it difficult to determine their actual impact. In this experiment, if a customer tips more or less due to a factor other than the server’s posture, such as the server's charisma or prior acquaintance with the customer, it is considered a confounding variable.

• Server recognition by frequent customers.
• Server's charisma or friendliness.
• Customer's previous dining experiences.

These confounding variables can obscure the real effect of the server's posture, leading to misleading conclusions.

Randomization

Randomization is a vital process in experimental design, as it helps to eliminate bias and ensure that each treatment is given a fair chance of being tested. In this experiment, the server flips a coin to decide whether to stand or squat, ensuring that neither the server nor the customers are influencing the choice consciously. This method protects against confounding variables as it randomly associates the variables with the treatments:

• Provides each treatment an equal chance of assignment.
• Limits biases from researchers or participants.
• Assists in obtaining unbiased and credible results.

Randomization, thus, enhances the reliability of the study's findings.

Blocking in Experiments

Blocking involves grouping similar experimental units and conducting treatments within these groups. While not necessary in this experiment, blocking could be beneficial if certain extraneous factors become problematic. If tips exhibit a pattern based on time or customer group, introducing blocking could help control these factors. For example:

• Conducting separate experiments during lunch and dinner.
• Segmenting customers by demographic criteria.

Blocking helps in reducing the variability within groups and making the effect of the treatment more apparent, providing clearer insights into the experimental results.