Sampling (technqiues)

• Random sampling is a method of selecting a sample from a population by selecting individuals from the population at random.
• Opportunity sampling is whoever is convinient and available at the time
• Systematic sampling is from a predetermined system, nth nu,ber
• Self selcted sampling is when the researcher selects participants from a list of people who have agreed to take part in the study
• Snowball sampling is a technique used to gather data from a small group of people to a larger group of people
• Stratified sampling is when participants are obti=ained from each of the strata in proportions to their occurance in the target populations
• random sampling


  +unbiased
• Opportunity


  +quick and easy

  _ may be baised as its from a small population
• Systematic

  +unbised as people are selected through a system

  _not truly random unlesss using random method
• Self-selected

  + gives access to a variety of people

  _ volunteer bias
• Snowball


  +researcher gets people who are diffuclt to contact

  _not likely to be a good cross-sections as the p's are friends of friends
• Stratified


  +more representative

  _ time consuming
• Target populations is the large group of people the researchers wish to study
• A sample is the small griuoof people who represent the targer populations and who are studied
• Representative is when the sampling of the participants is made up of peole who have the same chracteristics and abilities as the targer population
• Generalise refers to the extent to whihc we can apply findings of out research to the targer populations we are interested in
• Population validity is the extent to which the results of the study can be generalized to the population as a whole