AQA GCSE · Question 06.7 · Data Collection and Sampling Methods
What is not so good about Tom finding opinions in this way (opportunity sampling)?
How to approach this question
Think about the statistical disadvantages. Does this sample accurately reflect the entire population's views? Consider who is at a train station on a Saturday afternoon and who is not.
Full Answer
The sample is likely to be biased and not representative of the whole population. For example, people at a train station on a Saturday might be mainly shoppers or football fans, and may not represent the views of people who work on Saturdays, or those who live in rural areas.
The main disadvantage of opportunity sampling is that it is prone to bias, meaning the sample is unlikely to be representative of the target population. Tom's sample will only include people who are at Manchester Piccadilly on a Saturday afternoon and are willing to talk to him. This excludes many groups, such as:
- People who work on Saturdays.
- People who live in other parts of the country.
- People who avoid city centres or train stations.
- People in a rush who won't stop to answer.
The views of the people he samples may be very different from the views of the population as a whole.
Common mistakes
✗ Just saying "it is bad" without explaining why it is statistically weak.\n✗ Giving a practical disadvantage (e.g., "it might be noisy").
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