Sampling

• What is the purpose of sampling techniques?

  To choose a representative sample of the population
• What does it mean if a sample is representative?

  Results can be generalized to the wider population
• What is a potential issue with most samples?

  They contain some degree of bias
• What are the methods to select participants in a study?

  • Random sampling
  • Opportunity sampling
  • Volunteer sampling
  • Systematic sampling
  • Stratified sampling
• What is random sampling?

  Every member has an equal chance of selection
• What is a strength of random sampling?

  No investigator bias in participant selection
• What is a weakness of random sampling?

  It can be time-consuming to contact participants
• What is opportunity sampling?

  Participants who are accessible and willing are targeted
• What is a strength of opportunity sampling?

  It is easy and less time-consuming
• What is a weakness of opportunity sampling?

  The sample may not be representative
• What is volunteer sampling?

  Sample consists of self-selected participants
• What is a strength of volunteer sampling?

  It requires minimal input from the researcher
• What is a weakness of volunteer sampling?

  It may lead to volunteer bias
• What is systematic sampling?

  Every nth person is selected from a list
• What is a strength of systematic sampling?

  No investigator bias in participant selection
• What is a weakness of systematic sampling?

  It can be time-consuming to implement
• What is stratified sampling?

  Dividing the target group into sections
• What is a strength of stratified sampling?

  More representative than other methods
• What is a weakness of stratified sampling?

  Time-consuming to identify subgroups
• What are the steps in stratified sampling?

  1. Identify strata/sub-groups in the population
  2. Determine proportions of each strata
  3. Select sample randomly from each strata
• What are the strengths and weaknesses of each sampling method?

  • Random sampling:
  • Strength: Representative, no bias
  • Weakness: Time-consuming
  • Opportunity sampling:
  • Strength: Easy, less time-consuming
  • Weakness: May not be representative
  • Volunteer sampling:
  • Strength: Minimal input needed
  • Weakness: Volunteer bias
  • Systematic sampling:
  • Strength: No bias
  • Weakness: Time-consuming
  • Stratified sampling:
  • Strength: More representative
  • Weakness: Time-consuming
• What is the challenge presented in the study material?

  Identify sampling techniques and their strengths/weaknesses
• What should you do at the end of the session?

  Share a key takeaway on your way out