AQA Psychology Year 1 & AS ACTIVITY Cara Flanagan, Jo Haycock, Diana Jackson-Dwyer © Ill uminate Publishing 2015

Choosing a sampleChapter 6: Research methods Sampling

174–175

6.10

TO TAL = 20 marks

An occupational psychologist wishes to fi nd out how the employees in a fi rm feel about new proposals for important reorganisation with the fi rm. This fi rm consists of fi ve departments:

◾ The shop-fl oor workers 60% of the workforce

◾ The supervisors 10% of the workforce

◾ The offi ce staff 20% of the workforce

◾ The buyers 6% of the workforce

◾ The management 4% of the workforce

The total number of employees is approximately 1,000. The psychologist decides to use a sample of 50.

a. How would she select a random sample from the workforce? (2)

b. How would she select a stratifi ed sample? Be precise! (4)

c. For this investigation, which method of sampling would be better and why? (2)

d. Why are volunteer samples unlikely to be representative? (2)

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3The headteacher of a comprehensive school of 2500 pupils spread over fi ve year groups (no sixth form) wishes to fi nd out what students think of proposed uniform changes. The school is too large to obtain the opinion of all the students so he decides to use a sample size of 125.

a. What percentage of the target population is the sample? Show your working. (3)

b. How would he draw a systematic sample of the target population? (2)

c. How would he obtain a random sample of the students? (2)

Many publications, such as OK magazine, Heat, Psychology Today and Hello! have done surveys on the sexual habits of their readers. Readers are invited to send in a completed questionnaire (anonymously) to the magazine.

Think of at least three ways in which the sample so obtained is likely to be biased. (3)

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