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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." Journal of Applied 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 variables and how they could be controlled. c. Discuss whether blocking would be necessary. d. Identify possible confounding variables. e. Discuss the role of random assignment in this experiment.

Step by step solution

01

Identify Treatments and Response Variable

The treatments in this experiment are the two different postures of the server: standing or squatting. The response variable is the tip size that the server receives.

02

Identify and Control Extraneous Variables

Extraneous variables may include the demeanor of the waiter, the quality of the food, the time of day or week, or the personality of the customer. These could be controlled by ensuring that the waiter behaves consistently across all customers, the quality of the food is consistent, and the experiment is conducted at various time intervals.

03

Discuss the Necessity of Blocking

Blocking may or may not be necessary in this experiment. If there are groups of customers that are expected to react differently to server posture, then blocking would be advantageous to even out the effect of these groups on the response.

04

Identify Possible Confounding Variables

Some possible confounding variables include the type of meal ordered by customers (fancy or plain), the location of the table (quiet or noisy area), and customer mood during the meal.

05

Discuss the Role of Random Assignment

Random assignment is important in this experiment to ensure that both treatments (squatting and standing) are applied to a representative sample of customers, thus minimizing the impact of confounding variables. The coin flip used to decide whether the server will stand or squat is a form of random assignment.

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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 response variable is the size of the tip that the waiter receives. This is the key outcome researchers are interested in measuring. Essentially, the response variable is what they want to understand or predict in relation to the different treatments being applied.

For example, by altering the server's posture (either standing or squatting), researchers aim to see if there is a significant change or pattern in the tip amounts from the customers.

• It captures the effect of the server's posture on customer behavior.
• This variable is measured after the treatment to provide data for analysis.

Understanding the response variable helps in analyzing the effectiveness of an experiment and drawing valid conclusions from it.

Extraneous Variables

Extraneous variables are those additional factors that are not the focus of the study, yet they can influence the outcome.

In this tipping experiment, several extraneous variables could affect tipping behavior, such as the demeanor of the waiter, the quality of the food, or even the time of day.

• The waiter's mood or level of engagement might affect tips, irrespective of their posture.
• The quality or promptness of the meal can also sway customer generosity.
• Dining during busy hours might lead to different tipping than quieter periods.

To mitigate their impact, it’s essential to control these variables as much as possible, ensuring consistency. This can be achieved by maintaining the same quality of service and food throughout the study, and varying the time and place of the observation equitably.

Confounding Variables

Confounding variables are those that the experimenters might not initially spot, but can muddle the results by being closely linked to both the independent and dependent variables.

For this restaurant experiment, possible confounding variables might include the type of meal ordered, the location of the table, or the customer’s mood.

• Higher-priced meals may lead customers to tip more, regardless of server posture.
• A table in a noisy or uncomfortable location might lead to lower tips, skewing results.
• Customers' moods, influenced by factors beyond the server’s posture, could alter their tipping behavior.

Identifying and controlling for confounding variables is crucial to accurately assess the effect of different server postures on tipping, leading to more reliable conclusions.

Random Assignment

Random assignment is a cornerstone of experimental design, crucial for minimizing bias and ensuring reliable results. In this experiment, random assignment was achieved through the waiter flipping a coin to decide whether to stand or squat.

Random assignment is important because:

• It ensures that both the standing and squatting postures are applied across a diverse range of customer groups.
• This variability helps in balancing out any unforeseen influences on the response variable, making the results more generalizable.
• It reduces the impact of confounding variables by distributing them statistically evenly across treatment groups, leading to a fair comparison between postures.

Using a method like a coin flip achieves a simple yet effective randomization, crucial for the integrity of the study and the validity of its findings.