Studying Sociology GCSE and Sociology A Level 5: Sampling Methods in Sociology: Non-probability sampling


Here is the fifth in our series of study blogs for those studying A level Sociology and GCSE Sociology.

Non-Probability Sampling

This form of sampling is usually used when a sampling frame is not available. The sample is not selected randomly, so there can be issues as to how representative it is of the general population. Examples of non-probability sampling include:

  • Snowball – This is where the sociologist will make initial contacts. Say he/she wanted to study how much time 18-year old boys play computer games. He/she may ask a colleague to ask their students if they will take part. They find two participants from that group. They then ask these two participants if they know anyone aged 18 who might want to take part. That might lead to another four participants who are then asked if they know anyone, and so on. This can lead to bias, as it can mean that the first participants give them names of others who also play a lot of games and so on, so the selection can be biased. But this method can be very useful when trying to identify populations that are hard to reach – for example, people involved in illegal activities.
  • Quota – In quota sampling, the sample choice is made by the researcher. For example, they may be told to interview 20 18-year old boys on their use of computer games. So they may decide to go into their local town and ask the first 20 18-year old boys they see. This can obviously lead to bias, as they may select participants because they look friendly, they look like they might play computer games and so on.
  • Purposive– This is where sociologists will select a sample that is non-representative to get some rich information. This is usually in the form of a case study. So they may make their selection in either –
    • Deviant/Extreme sampling – where they select individuals who are extreme to study. OR
    • Typical case sampling – to study those who are typical of a particular group. Sociologists often use this form of sampling when they are trying to falsify a hypothesis. For example, if a sociologist thinks that women are less likely to have traditionally “female” jobs now, they may deliberately look at traditionally “female” jobs to see who is actually doing the jobs.

Tracey Jones

Sociology Tutor

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