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All 22 Flashcards — Sampling techniques
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Question
What is a sample?
Answer
The group actually studied, chosen to represent a larger population.
Question
What is a population?
Answer
The whole group the researcher wants their findings to apply to.
Question
What is random sampling?
Answer
Everyone in the population has an equal chance of being chosen — most representative.
Question
What is opportunity sampling?
Answer
Using whoever is available and willing at the time. Also called convenience sampling. Quick, but often unrepresentative.
Question
What is self-selected sampling?
Answer
People choose to take part, for example by answering an advert. Also called volunteer sampling.
Question
What is stratified sampling?
Answer
Choosing sub-groups in the same proportions as the population.
Question
What is snowball sampling?
Answer
Participants recruit others — useful for hard-to-reach groups.
Question
Why does sampling matter?
Answer
A biased sample limits generalisability — findings may only apply to that group.
Question
Representative vs practical techniques?
Answer
Random/stratified = more representative; opportunity/self-selected = more practical.
Question
Which concept does sampling link to?
Answer
Bias — an unrepresentative sample biases the findings.
Question
Target population vs sample?
Answer
Target population = everyone the study is about; sample = those who take part.
Question
What is a sampling frame?
Answer
A complete list of the target population, needed for random or stratified sampling.
Question
What is selection bias?
Answer
When the people chosen are not representative, because they self-select, the researcher picks them, or groups are excluded.
Question
Three types of external validity?
Answer
Population (other people), ecological (real-life settings), temporal (other times).
Question
Generalisability vs transferability?
Answer
Generalisability = applying results to the population (experiments); transferability = applying findings to a similar setting (qualitative).
Question
What are WEIRD samples?
Answer
Samples from Western, Educated, Industrialised, Rich, Democratic societies, which may not represent most people.
Question
Stratified sampling: one strength, one limitation?
Answer
Every subgroup is represented in proportion; needs detailed knowledge of the population to build the strata.
Question
Snowball sampling: one strength, one limitation?
Answer
Reaches hidden groups and builds trust; participants know each other, so the sample is not representative and privacy is harder.
Question
Random sampling: one strength, two limitations?
Answer
Everyone has an equal chance, so the sample tends to be representative; but it needs a full sampling frame, and a small random sample can still be unrepresentative by chance (sampling error). People who refuse cause non-response bias.
Question
Probability or non-probability sampling?
Answer
Probability: chance decides who takes part (random, stratified). Non-probability: it does not (opportunity, self-selected, snowball, purposive).
Question
What is purposive sampling?
Answer
Choosing participants on purpose because they have the characteristics or experience the study needs.
Question
What is non-response bias?
Answer
When the people who refuse or do not reply differ from those who take part, so the sample is tilted.
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