sampling

• random sampling

  = all people from the target population have equal chance of being selected (names in a hat)
• random sampling evaluation

  :) eliminates researcher bias = not choosing

  :( sample may not be truly representative = lacks population validity

  (may pull all females)

  :( requires a list of all people in the target population
• volunteer sampling


  = people within a sample frame reply to a request/advertisement
• volunteer sampling evaluation

  :) minimal effort for researcher

  :) likely to be motivated for the study

  :( biased by location/audience of ad

  :( low population validity + generalizability (only people interested would reply)
• systematic sampling

  = people from a larger population are selected at a fixed interval (database, every nth person)
• systematic sampling evaluation

  :) no researcher bias when selecting

  :) simple and easy to use on a wide scale

  :( may not be truly representative sample (all females)
• opportunity sampling

  = people are easily accessible, readily accessible and willing to take part (an existing class of students)
• opportunity sampling evaluation

  :) convenient and easy to collect ps (class of students)

  :( may be biased if researcher is more or less likely to choose a specific type of person

  :( less likely to have population validity (ps are a certain group of people)
• stratified sampling

  = dividing a population into smaller groups based on shared attributes or characteristics and an appropriate % that's representative of the group is selected

  (60% 1st yrs, 40% 2nd yrs = 6ppl 1st yr and 4ppl 2nd yr
• stratified sampling evaluation

  :) increased precision in selected ps

  :) can use on a wide scale

  :( difficult to analyse results