SAMPLING TECHNIQUES

• Sample:

  • Participants you select from a target population (group you are interested in)
  • Should be representative of the target population
  • Attrition - participants can drop out at any time (reduce sample size, unrepresentative sample
  • Could be biased
• Generalisation:

  • Application of the results from a study to the wider target population
  • Assumes that findings from the sample will be the same for everyone in the target population
• Volunteer Sample:

  • Participants pick themselves e.g. newspaper adverts
  • Quick and easy
  • May not have a representative sample (participants share similar characteristics) resulting in volunteer bias
• Opportunity Sample: 

  • Approaching people to take part in the study
  • Quick and easy 
  • Cheap
  • May not have a representative sample (participants share similar characteristics) resulting in volunteer bias
• Random Sampling:

  • Everyone in the target population has an equal chance of being selected 
  • Eliminates sampling bias
  • Participants may refuse to take part
  • Difficult to achieve (time, effort, money)
• Systematic Sampling:

  • Every nth person , need an order e.g. alphabetical
  • Objective (unbiased)
  • Difficult to achieve (time-consuming)
• Stratified Sampling:

  • Identify subgroups, select participants in proportion with their occurrences
  • Sample- highly representative of the target population- can generalise
  • Time-consuming
  • Can't reflect all ways people are different