Sampling

• Random

  1. identify all members of target population
  2. put all names in a hat
  3. draw blind
  4. allocate participants to conditions
• strength of random sampling

  • sample is likely to be representative
  • safely generalise findings to the target population
  • high external validity
• opportunity sampling

  1. researcher approaches potential participants and asks if they will take part
  2. those who agree form the sample
• volunteer sampling

  1. self selecting - participants approach researcher to take part in response to an advert

  weakness: confident and outgoing people likely to take part - findings can't be generalised
• stratified sampling

  1. identify all members of the target population
  2. identify sub groups relevant to the study
  3. randomly select from each category in the same proportion as in the target population e.g. if there are 60% female and 40% male then this should be the same in the study sample
• systematic sampling

  1. identify all members of the target population in a list
  2. determine nth number by dividing number of the target population by the number required in the sample