Participants and sampling methods Flashcards
What’s a sample?
A group of people who take part in the investigation. Those who are referred to as “participants”.
What’s sampling?
The process of selecting participants from the population.
What is random sampling?
A group is selected randomly so every member of target population has an equal chance at being selected.
Advantages and disadvantages of random sampling?
+ Method isn’t biased
- Sample may be unrepresentative of target population.
- Lowers the external validity.
What is self-selected sampling?
Relies on volunteers to make up the sample. Participants themselves come forwards to take part in the study.
Advantages and disadvantages of self-selected sampling?
\+ Participants are willing to participate with little effort on behalf of the experimenter. \+ Cost effective. - Volunteer bias can occur - Makes the sample unrepresentative - Generalisations are more difficult - Lowers external validity.
What is an opportunity sample?
Selecting people who are available at the time of the study.
Advantages and disadvantages of an opportunity sample?
+ Less time consuming
+ Cost effective
- Only taken from a small section of the target population so unrepresentative (E.G. if in a local primary school, may not include all ethnicities).
What is quota sampling?
Participants are selected according to their frequency in the population. Chosen to take part in research by the researcher.
Advantages and disadvantages of quota sampling?
+ Representative of population
+ Improves the external validity
+ So can be generalised.
- Can lead to researcher bias.
What is stratified random sampling?
Groups of participants are selected according to frequency in population. Within each group, individuals are selected randomly.
Advantages and disadvantages of stratified random sampling?
+ Representative of the population
+ Improved external validity
- Can be very time consuming
- Expensive
What is systematic sampling?
Every nth person is selected
Advantages and disadvantages of systematic sampling?
+ No researcher bias
- Method can be accidently unrepresentative.
What is snowball sampling?
Small number of participants are recruited, and then participants themselves recruit others to grow the population.
