Sampling techniques Flashcards
What is random sampling?
A sample in which all members of the target population have an equal chance of being selected to participate
What are the strengths of random sampling?
Quick
Easy
Investigator bias is avoided
What are limitations of random sampling?
Predicts that samples should be representative but this may not be the case
What is systematic sampling?
A mathematic selection of participants when the population size is divided by the sample size to dictate which participants are selected for the sample - every nth name from the sampling frame
What are the strengths of systematic sampling?
Only input from investigator is deciding the sample size, therefore avoids investigator bias
What are the limitations of systematic sampling?
There is the possibility that it is not representative of the whole sample, limiting generalisability
What is stratified sampling?
Aims to ensure that the key characteristics of the population are represented in the same proportion in the sample
What are the strengths of stratified sampling?
Guarantees all characteristics are represented
Representative so therefore generalisable
Avoids investigator bias
What are the limitations of stratified sampling?
Time consuming
If all features aren’t identified, it won’t be representative
What is opportunity sampling?
A sample of participants that were available at the time of selection.
What are the strengths of opportunity sampling?
Straightforward
Less time consuming
What are the weaknesses of opportunity sampling?
The researcher may consciously or unconsciously show bias in selection
Those available may not provide a representative sample
What is a volunteer sample?
A sample of participants who have self-selected to take part
What are the strengths of a volunteer sample?
Straightforward
Less time consuming
What are the weaknesses of a volunteer sample?
Sample bias - only certain types of people may want to volunteer, limiting generalisability
