Sampling techniques Flashcards
What is random sampling?
Everyone is placed in a list, and assigned a number which is selected randomly.
What are the strengths of random sampling?
・sample is unbiased and representative of target population
・same probability of being selected
What are the weaknesses of random sampling?
・time consuming to conduct
・some may refuse to take part
・representativeness not guaranteed
What is opportunity sampling?
Those who are available and willing to take part are selected.
What are the strengths of opportunity sampling?
・quick and convenient
・inexpensive
What are the weaknesses of opportunity sampling?
・within researchers control = researcher bias
・sample may not be representative
What is systematic sampling?
A predetermined system used to select participants.
What are the strengths of systematic sampling?
・selection process is structured so that researcher has no influence once system has been established.
・objective and unbiased
What are the weaknesses of systematic sampling?
・unbiased selection doesn’t guarantee unbiased sample
・could introduce hidden bias = unrepresentative sample
What is stratified sampling?
The population is divided into subgroups (stratas) based on characteristics.
What are the strengths of stratified sampling?
・most representative method
・finding is generalisable
What are the weaknesses of stratified sampling?
・stratas are time consuming
・identified stratas cannot always reflect differences = representativeness not always possible
What is volunteer sampling?
Participants are self-selected, usually through responses to advertisements or invitations.
What are the strengths of volunteer sampling?
・creating a sample requires little effort
What are the weaknesses of volunteer sampling?
・lacks generalisability
・volunteers eager to please, increases demand characteristics
