Question

Question 1

Main Street in Rexburg is a historic and economically important corridor in the small Idaho City. The mayor of Rexburg is considering the implementation of reverse angle parking along this road. Reverse angle parking a way of putting parking stalls so that motorists drive past the stall, and then back in at an angle. Studies have shown that this parking method results in a fewer accidents, compared to traditional angle parking. Business owners are concerned that some residents would avoid the new parking stalls, and that it would negatively impact their sales. A group of lntroductory Statistics students is invited to survey a simple random sample of city utility customers to determine how their desire to shop on Main Street could be impacted if reverse angle parking was implemented. The mayor has a list of all 1200 of the city utility customers. Describe how a Simple Random Sample of 50 utility customers could be obtained.

Question 2

A group of 824 statistics students enrolled at a private 4-year university were asked to write down a random integer between 1 and 20. Very few people chose the number 1 (less than 1%) The most common numbers were 7 (10%), 13 (11%), and 17 (13%) How effective are students at generating random numbers? (Source: Craig Johnson) [Explain how you can tell from the given data]

Question 3

A student wants to estimate the prevalence of illicit drug use on campus. Using the student directory, he obtained a SRS of students. He telephoned each randomly selected student and as part of the survey asked “In the last 12 months, have you ever used Illegal drugs?" Discuss at least one potential problem with this study.   

Question 4

Researchers conducted a double-blind placebo-controlled, repeated-measures experiment to compare the effectiveness of a commercial caffeinated carbohydrate-electrolyte sports drink with a commercial non-caffeinated carbohydrate-electrolyte spots drink and a flavored-water placebo. Sixteen highly trained cyclists each completed three trials of prolonged cycling in a warm environment: one while receiving the placebo, one while receiving the non-caffeinated sports drink, and one while receiving the caffeinated spots drink. For a given trial, one beverage treatment was administered throughout a 2-hour variable-intensity cycling bout followed by a 15-minute performance ride. Total work in kilojoules (kJ) performed during the final 15 minutes was used to measure performance. The beverage order for the individual subjects was randomly assigned. A period of at least 5 days separated the trials. All trials took place at approximately the same time of day in an environmental chamber at 28.5 and 60% relative humidity with fan airflow of approximately 2.5 meters per second (m/s).

The researchers found that cycling performance, as assessed by the total work completed during the performance ride, was 23% greater for the caffeinated sports drink than for the placebo and 15% greater for the caffeinated sports drink than for the non-caffeinated sports drink. Cycling performances for the non-caffeinated sports drink and the placebo were not significantly different. The researchers concluded that the caffeinated carbohydrate-electrolyte sports drink substantially enhanced physical performance during prolonged exercise compared with the non-caffeinated carbohydrate-electrolyte spots drink and the placebo. (Source: Kirk J Cureton, Gordon L Warren et al. 'Caffeinated Sports Drink Ergogenic Effects and Possible Mechanisms," International Journal of Sport Nutrition and Exercise Metabolism, 17(1):35-55, 2007)

a. What does it mean for the experiment to be placebo-controlled?

b. What does it mean for the experiment to be double-blind?

c. Why do you think it is necessary for the experiment to be double-blind?

d. How is randomization used in this experiment?

e. What is the population for which this study applies?

f. What is the sample?

g. What are the treatments?

h. What is the response variable?

Answer 1