sampling

• population


  entire group of individuals/ instances that share a set of characteristics and focus on the research
• sample


  a subset/ smaller group of the population that is selected to participate in the research
• representativeness


  how accurately a sample reflects the characteristics of the larger population
• random sampling 


  every member of the population has an equal chance of being selected (e.g. random number generator)
• strengths of random sampling

  unbiased - all members of the target population have an equal chance of selection

  possible to choose a specific subgroup in the target population first, which makes it easier to randomly select participants
• weaknesses of random sampling

  can be difficult to access a complete list of the population

  time consuming and may result in logistical challenges if selected participants are hard to reach
• opportunity sampling 


  participants are selected based on the convenience and availability at the time of the study
• strengths of opportunity sampling

  quick and easy to gather participants, especially for small scale studies

  cost effective
• weaknesses of opportunity sampling

  highly prone to bias as the sample may not represent the population

  limited generalisability
• stratified sampling 


  population is divided into sub groups based on shared characteristics and participants are randomly selected from each sub group
• strengths of stratified sampling

  ensures representation of key groups in the sample improving generalisability

  reduces sampling bias
• weaknesses of stratified sampling

  time consuming and complex to divide population into strata

  requires detailed knowledge of the populations characteristics to define strata
• volunteer sampling


  participants self select to take part in a study, often responding to and ad or call for participation
• strengths of volunteer sampling

  easy to obtain participants saving time and effort

  may attract participants who are genuinely interested and motivated
• weaknesses of volunteer sampling

  likely to lead a biased sample (e.g. those with free time or a strong interest)

  results may not be generalisable to the wider population