Sampling

• Sampling


  Involves selecting participants from a target population. The different sampling techniques include: Random, systematic, stratified, opportunity and volunteer
• Random Sampling 


  Every member of the target population has an equal chance of being selected
• Systematic Sampling 


  A predetermined system used to select participants
• Stratified Sampling


  Subgroups within a population are identified. Participants are obtained from each category in proportion to their occurrence within the population
• Opportunity sampling


  Consists of selecting anyone who is available and willing to take part in the study
• Volunteer Sampling


  Consists of participants self-selecting to take part in a study by either volunteering when asked or by responding to an advert
• Strength of random


  Likely to be representative so can be generalised to the target population
• strengths of systematic


  not subject to researcher bias as a numerical value is assigned to each person on a given list and then selected according to their Nth position; without any personal preference from the researcher
• strengths of stratified 


  likely to be representative as each subsection of the target population is proportionally represented, so results can be generalised to the wider population with more confidence that they apply
• strengths of opportunity


  quicker and easier to obtain in comparison to the other methods
• weakness of random 


  difficult and time consuming to get the full details of the target population. People that are selected may be unwilling to take part
• Weakness of systematic 


  not truly unbiased as every nth person selected ,may have a similar trait in common and therefore will not be representative of the wider population
• weakness of stratified 


  difficult and time consuming to identify subgroups. People that are selected may be unwilling to take part
• weakness of opportunity


  high chance that the sample will be biased
• weakness of volunteer 


  a particular type of person is likely to take part in research. Therefore the sample is likely to be biased