Sampling methods

• Sampling is using a small group of people to be representative of a target population
• • Opportunity sampling is taking the sample from people who are available at the time the study is carried out and fit the criteria you are looking for
• • Random sampling is a sampling method in which every member of the target population has an equal chance of being chosen
  • This involves identifying everyone in the target population and then selecting the number of participants you need in a way that gives everyone in the population an equal chance of being picked (names in a hat)
• • Stratified sampling is when subgroups within a population are identified
  • Participants are obtained from each of the strata
  • Selection from the strata is completed using a random technique (names in a hat)
• Systematic sampling is using a predetermined system to select participants (every 6th person from a phonebook)

  The numerical interval selected would be applied consistently
• • Volunteer sampling is when participants become part of a study because they volunteer when asked or in a response to an advert
• • Opportunity sampling is the most practical and cheapest way to ensure you have a large sample which increases the chance that conclusions drawn may have relatively high population validity
  • Your sample is likely to be biased in some way which may lower the generalisability of your findings
  • Researcher bias is possible when taking an opportunity sample, the researcher may got to a place where they expect to find people that will help them achieve a result they have predicted
• • Random sampling doesn't 100% guarantee a representative sample is gained
  • The method offers a good chance of gaining a representative sample
• • Stratified sampling is more like to be representative of the target population than other methods due to proportional representation and the random sampling
  • It is very time consuming and expensive (to identify strata and randomly select from strata)
• • Systematic sampling avoids researcher bias
  • It is usually a fairly representative
  • It is still possible to be an unrepresentative sample
• • Volunteer sampling is an efficient way of gaining a large research sample because participants approach the research group which is cost-effective
  • Research found that a particular type of person is likely to volunteer. There a volunteer sample is unlikely to be representative of your entire target population
• Target population


  The group of people you wish to investigate. This is the group of people from whom the sample must be drawn