0.6. Sampling Flashcards
Opportunity sampling
People who are available to take part in research and accessible to the researcher
(Anyone around at the time)
E.g. asking people around college
Strengths of opportunity sampling
- quick and easy way to obtain ppts
Weaknesses of opportunity sampling
- researcher biased sample (in terms of age or background)
- not always representative of a target population
- difficult to generalise
Random sampling
Where every member of the target population has an equal chance of being chosen for the sample
E.g. putting all names from target population into hat then drawing the 1st 10 names in condition 1 and next 10 in condition 2
Strengths of random sampling
- not biased
- more likely to be representative of the target population
Weaknesses of random sampling
- randomly selected ->may not be representative
- time consuming
Stratified sampling
- involves researchers first identifying the different sub groups of people in the population and then drawing ppts from each sub group- pick out proportions
E.g. Tesco has lots of different types of worker there (till, shelves, managers, admin)- identity groups, find proportions and take a sample from each
Strengths of stratified sampling
- all subgroups are representative
Weaknesses of stratified sampling
- very time consuming
- sometimes difficult to identify subgroups
Systematic sampling
Use a predetermined system to select ppts
Every nth person
E.g. picking every 6th person from the yellow pages
Strengths of systematic sampling
- unbiased ppts are selected - objective system
-simple and saves time/ money
Weaknesses of systematic sampling
- not truly unbiased unless you select a number using random method and start with this person, and then select every nth person
Volunteer sampling
Where people offer their time to be in the study
Usually have an interest
E.g. advertise in the newspaper
Strengths of volunteer sampling
- access to a variety of ppts which would make the sample more representative
- saves time when looking for ppts
Weaknesses of volunteer sampling
- biased as ppts are likely to be highly motivated with extra time on their hands