People who provide an answer to telephone surveys typically listen to an interviewer's introductory remarks, and then decide if they want to continue or hang up. Suppose that a study made telephone calls to randomly selected households and asked about opinions for an upcoming election. To investigate responses, the interviewer sometimes gave her name, in others she identified the university she enrolled in, and in still others she identified both herself and her university. The study recorded the percentage of each group of interviews that was fully completed.

a) Is this telephone survey an example of an observational study or an experiment?

b) What are the explanatory and response variables for this survey?

A clinical trial was created to study sinus infections. The experimental design is a completely randomized experiment that assigned 250 patients at random among four treatments as given below:

Antibiotic PillPlacebo Pill

Steroid Spray5364

Placebo spray6568

a) Provide an outline for this experimental design.

b) Describe how you would label the 250 subjects.

c) Explain briefly how you would perform the random assignment of patients to treatments. Assign the first five patients who will receive the first treatment.

A business PhD student who lived on a naval base, looked at prices of items at the Naval Commissary and prices of the same items at Kmart. Assume that these are a random sample of items 10 items. The student wanted to test the hypothesis that the mean price at the naval base was less than the mean price at Kmart.

ItemsKmartNavy

Tide19.9918.13

Clorox4.292.57

Gain5.395.13

Swiffer 7.995.99

Pledge2.992.48

Secret3.992.94

Spam2.491.30

Pepsi1.491.38

Chunky 1.791.29

Water1.500.99

a) Provide an outline for the design of this experiment.

b) Identify the response variable.

c) Use statistics to investigate the results.

d) Determine if you can reach a definitive conclusion.

Independent random samples from four different brands of recently produced batteries were placed on a life test. The following lifetimes (in minutes) were recorded.

Brand ABrand BBrand CBrand D

110118108117

113116107112

108112112115

115117108119

112119109118

a) Provide an outline for the design of this experiment.

b) Identify the response variable.

c) Is there any evidence that the sample data contradicts the claim that there are no differences in the average lifetime of these four brands?