2.2.2 - 2.2.10 Methodology: Sampling Flashcards
What are the 4 sampling methods?
Random, opportunity, volunteer, and stratified
What is random sampling?
Where the subset of individuals all have the same probability of being chosen
What is opportunity sampling?
Uses people from target population available at the time + willing to take part
What is volunteer sampling?
Where ppts self select to become part of study because they volunteer when asked, or respond to an ad
What is stratified sampling?
Involves categorising population into subgroups + taking a representative proportion of each
What is the strength of random sampling?
Unbiased - equal chance of selection
What are the weaknesses of random sampling?
Cant control extraneous variables, often not random - ppts assessed
What is the strength of opportunity sampling?
Takes little prep
What is the weakness of opportunity sampling?
Biased - from a small part of whole population
What are the strengths of volunteer sampling?
Doesnt violate informed consent + deception (aims are exposed), can get specialised group of ppts
What are the weaknesses of volunteer sampling?
Demand characteristics - seen ad so know aims, biased - volunteers with extra time more motivated to help than those who don’t
What is the strength of stratified sampling?
Most representative of all sampling techniques
What are the weaknesses of stratified sampling?
Decisions abt subgroups used may be biased, lengthy process - might not agree to take part
