Charity workers were doing research into differences in the health of families in Chennai, a city in India. They worked in two densely populated areas of the city which are both shown in Fig. 1.1 (below). One was an area of unplanned housing (squatter settlement) and the other was another area of poor quality housing which was planned and permanent.
The researchers wanted to find out if the following hypotheses were correct:
Hypothesis 1: Diseases were more common in the area of unplanned housing than in the area of permanent housing.
Hypothesis 2: Most residents in both areas used government health facilities.
To investigate the two hypotheses the researchers used a questionnaire with a representative sample of people who lived in each area. The sample size (number of people who answered the questionnaire) was 100 in each area.
(i)
Why did the researchers need to use a sample of people?
[1]
(ii)
Information which is collected using a questionnaire is known as ‘primary data’. What does ‘primary data’ mean?
[1]
(iii)
The following is a poor sampling method which may have been used to get a representative sample of people to answer the questionnaire.
‘Give the questionnaire to all mothers who the researchers met outside the local school.’
Explain why this is a poor method to obtain a representative sample.
[3]
(iv)
Describe a good sampling method which the researchers could use to choose a representative sample of people to answer the questionnaire. Explain why this would be a good method to use.
[3]
