Sampling Methods

• Random sampling

  Gives each member of the population an equal chance of being selected
• Stratified sampling

  Creating a sample that's similar to your target population by using percentages -> percentage in the sample is the same as the entire population
• Opportunity sampling

  Sampling whoever is around at the time -> nearest and most convenient people that are willing to take part
• Volunteer sampling

  Having people volunteer to take part in the experiment

  -> putting up a poster/advert asking for ppts to self-select themselves and take part in your research
• Strengths of random sampling

  • All members have an equal chance of being selected
  • quick
• Weaknesses of random sampling

  may have more of a minority group and thus not be representative of the wider population

  had to recreate
• Strengths of stratified sampling

  Sample is spread evenly throughout groups in the population -> accurate representation
• Weaknesses of stratified sampling

  • Can be very time consuming
  • categories have to be identified and calculated -> not easy to categorise people, may ignore important strata
  • requires details from the population
• Strengths of opportunity sampling

  Easiest and most convenient method
• Weaknesses of opportunity sampling

  Unrepresentative, sample is drawn from a small population
• Strengths of volunteer sampling

  • ppts less likely to drop out (committed)
  • ppts are willing to partake
• Weaknesses of volunteer sampling

  • Only tend to attract outgoing people with an interest in research -> only get results from those who volunteer, which may not be representative of the larger population
  • factors may affect who takes part
  • may not get high enough numbers