Sampling

Question 1

Explain the difference between a population and a sample (3 marks)

Answer 1

A population refers to the large group of people that the researcher is interested in investigating - a subset of the general population - whereas a sample refers to a smaller group of people used in a research study that are taken from the target population and are usually representative of said population so that findings can be generalised.

Question 2

Explain what is meant by ‘random sampling’ (2 marks)

Answer 2

Random sampling is when every person in the target population has an equal chance of being selected.

Question 3

Outline one strength and one limitation of systematic sampling (2 marks)

Answer 3

One strength of using systematic sampling is that there is no chance of researcher bias. Because the researcher has no control over who is selected, we can be more sure that the manipulation of the IV caused results as opposed to a biased selection.
One weakness of using a systematic sample is that it is not completely representative of the target population, meaning that findings may not be able to be generalised fully.

Question 4

Explain how you could select a stratified sample of male and female students within a school or college (3 marks)

Answer 4

1) Determine the ratio of male students to female students in the school.
2) Use this ratio to calculate the number of male and females in your sample size.
3) Randomly select participants in the correct proportions.

Question 5

Explain one reason why generalisations from an opportunity sample would be difficult (2 marks)

Answer 5

Ann opportunity sample is taken from a very specific area, such as one town/street so the sample is therefore unrepresentative of the target population and cannot be generalised.