Sampling Flashcards
What is opportunity sampling?
Selecting whoever is available e.g. ask people who pass you by on the street
What is a strength of opportunity sampling?
The easiest and quickest method because you use the first participants you find
What is a weakness of opportunity sampling?
It is biased because the sample is drawn from a very small part of the population
What is volunteer sampling?
Advertise for participants to volunteer e.g. poster or ad in newspaper
What is a strength of volunteer sampling?
Gives access to a wider variety of participants
What is a weakness of volunteer sampling?
It is biased as the potential participants are more likely to be highly motivated individuals who have lots of time on their hands
What is random sampling?
Put names or numbers in a hat and draw out the required number
What is a strength of random sampling?
More chance of getting a more balanced ‘representative’ group
What is a weakness of random sampling?
End up with a biased sample e.g. more males than females as the starting sample is too small
What is stratified sampling?
A small scale reproduction of a population
What is a strength of stratified sampling?
More chance of getting a more balanced ‘representative’ group as the selection comes from representative sub-groups within a population
What is a weakness of stratified sampling?
Take lots of time and money to do and some sub-groups may be missed. It can be difficult to identify traits and characteristics effectively enough to stratify the sample properly
What is systematic sampling?
Taking every nth person from a list to create a sample. This means that you have to calculate the size of the population then assess what size the sample needs to be to work out what the sampling interval is
What is a strength of systematic sampling?
No bias in selection, increasing the chances of getting an unbiased and therefore a representative sample. It will be generalisable
What is a weakness of systematic sampling?
Some sub-groups may be missed, in which case it will not be representative
