sampling

• what is a population?


  A group of individuals a researcher is interested in. At the end of the study the researcher wants to be able to make a statement about this population of people.
• what is a sample?


  A group of people who take part in a research investigation. The sample is drawn from a target population and is presumed to be representative of that population.
• what is generalisation?


  The extent to which findings and conclusions from a particular investigation can be broadly applied to the population
• what is bias in the context of sampling?


  When certain groups are under/over represented within the sample selected. This limits the extent to which generalisations can be made to the target population.
• what is random sampling?


  Where all members of a target population have an equal chance of being selected
• what is the method of random sampling?


  -a complete list of all members of a target population is obtained

  -all names on a list are assigned a number

  -the sample is generated using a lottery method
• what are the strengths of random sampling?


  -less risk of bias- the researcher has no choice over who is chosen

  this means random sampling could have higher gneralisability because the sample is more likely to be representative of the target population.
• what are the weaknesses of random sampling?


  -issues with generalisability- it is difficult to ensure everyone is included in the sample

  this could lead to a lack of external validity
• what is systematic sampling?


  where every nth member of the target population is selected
• what is the method systematic sampling


  -a complete list of all members of the target population is organised in some way (e.g alphabetically)

  -a sampling system is nominated (decision of what n equates to)

  -sample is generated
• what are the strengths of systematic sampling?


  -less likely to be subject to biased- the researcher has no control over who is selected

  this increases the generalisability and external validity of the findings.