Sampling Techniques Flashcards
What is a ‘target population’
A group of people researchers are studying and want to generalise their results to
What do samples need to be to be able to generalise the findings
Representative of the population
What is random sampling
When every member of the target population has the same chance of being selected e.g. names in a hat
Advantages of random sampling
- sample is likely to be representative (esp if big) and therefore results can be generalised
- no risk of researcher bias
Disadvantages of random sampling
- sometimes difficult to get full details of a target population from which to select a sample e.g full list of all people in the UK - some unregistered etc
- sample can be unrepresentative as not all members of the target population who are selected may be available or willing to take part
What is systematic sampling
A sampling strategy where participants are selecting by taking every Nth person from a list
Advantage of systematic sampling
- simpler + less effort than than other methods (e.g random) as only a list of the target population needed
Disadvantage of systematic sampling
- the process of can interact with a hidden periodic trait within the target population
-> If the sampling technique coincides with the periodicity of the trait, the sampling technique will no longer be representative.
What is stratified sampling
Stratified sampling involves classifying the target population into categories and then randomly choosing a sample that consists of participants from each category in the same proportions as they appear in the target population
Advantage of stratified sampling
The strength of stratified sampling is that all groups within a target population are included, therefore the sample should be representative of the target population.
Disadvantage of stratified sampling
Stratified sampling can be very time consuming as the categories have to be identified and calculated. If you do not have details of all the people in your target population you would struggle to conduct a stratified sample.
What is opportunity sampling
Opportunity sampling involves selecting participants who are readily
available and willing to take part.
- AKA convenience sampling
Advantages of opportunity sampling
This is the easiest and most practical method of ensuring large samples especially compared to stratified
Disadvantages of opportunity sampling
There is a high chance that the sample will not be representative of the target population.
-> Sometimes people feel obliged to take part in research (e.g. if they know the researcher) even when they do not really want to, this is unethical
What is volunteer sampling
Volunteer sampling involves people self-selecting to participate in a study. The researcher will usually advertise for people to take part in their research.
