Week 1 Questions

1.3 The manager of a bank with 12000 customers commissions a survey to gauge customer views on internet banking, which would incur lower bank fees. In the survey, 21% of the 300 customers interviewed said they are interested in internet banking.

a What is the population of interest?

b What is the sample?

c Is the value 21% a parameter or a statistic?

1.4 A light bulb manufacturer claims that less than 5% of his bulbs are defective. When 1000 bulbs were drawn from a large production run, 1% were found to be defective.

a What is the population of interest?

b What is the sample?

c What is the parameter?

d What is the statistic?

e Does the value 5% refer to the parameter or to the statistic?

f Is the value 1% a parameter or a statistic?

g Explain briefly how the statistic can be used to make inferences about the parameter to test the claim.

2.4 Information concerning a magazine's readership is of interest both to the publisher and to the magazine's advertisers. A survey of 500 subscribers included the following questions. For each question, determine the data type of possible responses.

a What is your age?

b What is your gender?

c What is your marital status?

d Is your annual income less than $30000, between $30000 and $60000, or over $60 000?

e To how many other magazines do you subscribe?

f How do you rate the feature article published in the current issue of the magazine (very good, good or poor)?

2.8 Residents of a high-rise block of flats in Perth city were recently surveyed and asked a series of questions. Identify the type of data for each question.

a What is your age?

b On which floor do you live?

c Do you own or rent?

d How many bedrooms are there in your flat?

e Does your block have a pool?

f How would you rate your satisfaction with the common facilities (e.g. swimming pool, tennis court) available to the residents (very good, good or poor)?

2.15 a Briefly describe how you might design a study to investigate the relationship between smoking and lung cancer.

b Is your study from part (a) observational or experimental? Explain why.

2.16 a List three methods of conducting a survey of people.

b Give an important advantage and disadvantage of each of the methods listed in part (a).

2.17 List five important points to consider when designing a questionnaire.

2.18 For each of the following sampling plans, indicate why the target population and the sampled population are not the same.

a In order to determine the opinions and attitudes of customers who regularly shop at a particular centre, a surveyor stands outside a large department store in the centre and randomly selects people to participate in the survey.

b A library wishes to estimate the proportion of its books that have been damaged. They decide to select one book per shelf as a sample, by measuring 30 cm from the left edge of each shelf and selecting the book in that location.

c A political surveyor visits 200 residences and asks the eligible voters present in the house at the time whom they intend to vote for. The visits take place during the afternoons.

2.21 The operations manager of a large plant with four departments wants to estimate the employee working hours lost per month due to accidents. Describe a sampling plan that would be suitable for estimating the plant-wide loss and for comparing departments.

2.22 A large university campus has 60000 students. The president of the students' association wants to conduct a survey of the students to determine their views on an increase in the student activity fee. She would like to acquire information about all the students but would also like to compare the school of business, the faculty of arts and sciences, and the graduate school. Describe a sampling plan that accomplishes these goals.

2.23 A telemarketing firm has recorded a list of the households that have purchased one or more of the company's products. These data number in the millions. They would like to conduct a survey of purchasers to obtain information about their attitude concerning the timing of the telephone calls. The president of the company would like to know the views of all purchasers, but would also like to compare the attitudes of people in the west, south, north and east. Describe a suitable sampling plan.