Sampling

• What is the target population?


  A group of people from whom a sample is selected
• 


  Biased sample - cannot be generalised to the target population because it contains participants not representative of the sample
• Biased sample has low...?


  population validity
• Selected from a list?

  random sampling, stratified sampling, systematic sampling
• Not selected from a list?

  opportunity sampling, volunteer sampling
• Random sampling?


  randomly selecting participants from the list
• Random sampling is more representative in ... groups?


  larger
• Stratified sampling?


  participants randomly drawn from a list until they meet the desired ratio e.g if 40% of the target pop are female, 40% of the sample size need to be female
• Systematic sampling?


  selecting every nth participant from a list
• Opportunity sampling?


  getting a sample group depending on the availability of people e.g asking people who walk past
• Volunteer sampling?


  Self selecting to volunteer from an advert or poster etc.
• what is the most representative?


  stratified
• Which ones are biased?


  stratified, systematic
• What bias doe opportunity sampling have?


  double bias
• What bias does volunteer sampling have?


  single bias
• Which is quick and easy?


  volunteer