AO1 - Sampling Techniques

• Random Sample: Every person in the target population has an equal chance of being selected
• How to conduct a random sample:

  1. Create a complete list of all the target population
  2. Write names (AO2) on equal size pieces of paper and put into a hat
  3. Without looking, select the number (AO2) you want in your sample from the hat
• Systematic sample: A 'system' is used to select participants
• How to conduct a systematic sample:

  1. Create a sampling frame to organise the target population, e.g. put all the people in the target population in alphabetical order
  2. Decide on the system, e.g. every 5th person is chosen until there are enough participants for the sample
• Stratified sample: An advanced way of sampling where the make-up of the sample reflects the proportions of certain sub-groups in the target population

  • e.g. if 70% of the target population are female, then 70% of the sample will also be female
• How to conduct a stratified sample:

  1. Identify the different sub-groups that make up the population, e.g. males/females
  2. Calculate how many of each proportion you would need for your sample size
  3. Number of participants which make up each proportion are chosen using random sampling
• Stratified sampling:

  • If the scenario gives you the percentages - (Sample size wanted/100) x percentage size of sub group
  • If the scenario doesn't give you percentages - (Sample size wanted/Target population size) x sub group size
• Opportunity sample: Being there at that moment in time
• How to conduct an opportunity sample:

  1. Go somewhere you have access to the population you want to study
  2. Ask the first 30 people who are there at that moment in time if they want to participate
• Volunteer sample: 'Self selected' method where people volunteer themselves to be participants
• How to conduct a volunteer sample:

  1. Place an advert where people in the target population will see it
  2. Wait for the first 30 replies