What is a target population?
The entire group of people that a researcher wants to study and generalise findings to.
Why is defining a target population important?
It ensures the research has clear generalisability and appropriate sampling methods.
What is a sampling frame?
A list of all members of the target population from which a sample is drawn.
Limitation of a sampling frame?
It may be incomplete or biased, leading to unrepresentative samples.
What is random sampling?
A sampling method where every member of the population has an equal chance of being selected
Strengths and weaknesses of random sampling?
Reduces sampling bias
More representative sample
− Time-consuming
− Requires a complete sampling frame
What is opportunity sampling?
Selecting participants who are readily available to the researcher
Strengths and weaknesses of opportunity sampling
Quick and convenient
Easy to carry out
− High sampling bias
− Low generalisability
What is systematic sampling?
Selecting participants at regular intervals (e.g. every 10th person)
Strengths and weaknesses of systematic sampling?
More structured than opportunity sampling
Reduces some bias
− Can still be biased if list is ordered in a pattern
What is stratified sampling?
The population is divided into subgroups (strata), and participants are selected proportionally.
Strengths and weaknesses?
Highly representative
Reduces sampling bias
− Time-consuming and complex
− Requires accurate population data
What is quota sampling?
Participants are selected to match certain proportions (quotas) of characteristics.
Strengths and weaknesses?
Ensures representation of key groups
Quick and practical
− Still relies on researcher choice → bias
− Less rigorous than stratified sampling
What is self-selected sampling?
Participants volunteer themselves to take part (e.g. responding to adverts).
Strengths and weaknesses?
Access to motivated participants
Easy to recruit
− Volunteer bias (e.g. people with strong opinions)
− Not representative
What is snowball sampling?
Existing participants recruit other participants from their networks.
Strengths and weaknesses?
Useful for hard-to-reach populations
Builds trust between participants
− Highly biased
− Participants may be similar → low generalisability
What is event sampling?
Recording a behaviour every time it occurs.
What is time sampling?
Recording behaviour at fixed time intervals (e.g. every 30 seconds).
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milgram and Kohlberg34
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research methods32
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methodologies54
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location of research16
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sampling20
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experimental design9
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levels of measurement11
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graphical representation18
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descriptive statistics11
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inferential statistics24
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reliability and validity22
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ethics21
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personal investigation x277
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role of the scientific community in validating new knowledge12
