Sampling techniques Flashcards
Define ‘sampling’
A method used to gather participants for research
Define ‘sample’
A group of people who are selected to represent the wider population
Define ‘representative sample’
A sample that closely matches the population being studied in as many ways as possible
Define ‘population’
The total number of people in a particular group/area
Define ‘target population’
The group of people from which a sample is drawn to represent them in as many ways as possible
What are the four types of sampling?
1) Random
2) Stratified
3) Volunteer
4) Opportunity
What is a random sample?
A random sample is members of the target population selected without any bias
How can a random sample be obtained?
By giving everyone in the target population a number then using a random number generator
What is a strength of random sampling?
1) Unbiased as all members of the target population have equal chance of selection
What are two weaknesses of random sampling?
1) Slow and inconvenient process
2) Sample may be unrepresentative
What is a stratified sample?
A stratified sample is members of the target population selected in an unbiased way but is guaranteed to be representative in certain ways
How can a stratified sample be obtained?
Participants are selected from different subgroups in the target population in proportion to the subgroups frequency in that population
- For example, the target population = 60% female and 40% male so the sample = 60% female and 40% male participants
What are two strengths of stratified sampling?
1) Representative as all subgroups are represented and are represented in proportion to the target population
2) No bias
What are 2 weaknesses of stratified sampling?
1) Slow and inconvenient process
2) Important subgroups (strata) may be ignored
What is a volunteer sample?
A sample of participants produced by asking for people willing to take part
When are volunteer samples most frequently used?
In lab experiments
How can a volunteer sample be obtained?
Through advertisements in a newspaper
What is an example of volunteer sampling in social psychology?
Milgram’s 1963 obedience study
- Milgram advertised for volunteers in the local newspaper, offering $4 for men who would take part in a memory experiment
What are 2 strengths of volunteer sampling?
1) Convenient way of finding willing participants
2) No experimenter bias
What are 2 weaknesses of volunteer sampling?
1) May be unrepresentative as only certain people may volunteer such as those interested in psychology or those who have a lot of free time
2) Sample may be more willing / committed which may show inaccurate results
What is an opportunity sample?
A sample of participants produced by selecting people who most easily available at the time of research
When are opportunity samples most frequently used?
In natural experiments or naturalistic observations
How can an opportunity sample be obtained?
Asking the first 10 people who walk past to fill out a questionnaire
What is an example of opportunity sampling in social psychology?
The Robbers Cave experiment
- Sherif sent his observers out to schools looking for boys who fit the profile of being white, athletic and confident.
- Sample was limited to boys that caught the observers attention and the school that the observers went to
What is a strength of opportunity sampling?
1) Most convenient and cheap
What are two weaknesses of opportunity sampling?
1) Low generalisability due to biased sample of people in the same place at the same time who share similar traits so may not represent a wider population
2) Low validity due to experimenter bias
