Sampling

• What is the population?


  A group of people who are the focus of the researcher's interest.
• What is a sample?


  A group of people who take part in reasearch.
• What is bias?


  When certain groups of people are under- or over- represented.
• What is generalisation?


  The extent to which findings and conclusions from a particular investigation can be broadly applied to the population.
• What is Opportunity Sampling?


  Those who are available and willing to take part at the time.
• + and - of Opportunity Sampling

  + Quick, easy and convenient

  -Researcher bias

  -Unrepresentative of target population
• What is Random Sampling?


  Each individual has an equal chance of being chosen.
• + and - of Random Sampling

  + Free from research bias

  -Time consuming

  -Can be difficult to obtain a list of target population
• What is Systematic Sampling?

  Every nth member of the target population is selected.
• + and - of Systematic Sampling

  + Avoids researcher bias

  -Can also be difficult and time consuming

  -More effort and money
• What is Stratified Sampling?


  The researcher identifies the different types of people in the target population and can work out the proportion of each.
• + and - of Stratified Sampling

  + Avoids researcher bias

  + Designed to be representative

  -The sub-groups cannot reflect ALL the ways people are different
• What is Volunteering Sampling?


  Participants put themselves forward for research (usually through adverts)
• + and - of Volunteer Sampling

  + Easy, less effort

  -Volunteer bias

  - attracts a certain profile e.g. those who are willing to stay after

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