Sampling Methofd Flashcards
Research population
The group of people the researcher wants to study.
They CANNOT study everyone so they have to select a sample.
Sample
A small group of people who represents the target population and who are studied
The sample must be:
REPRESENTATIVE of the target population
Sampling frame
The list of all members of the research population.
E.G a school list of all the names of the pupils/ staff, electoral roll
Benefits of having a representative sample
You can generalise the result of your study to the wider population
Probability sampling
The selection of a sample from a population
Each person in the sampling frame has an equal chance of being selected
Done when a sample frame IS available
EXAMPLES of probability sampling
Random sampling
Systematic sampling
Stratified sampling
Non- probability sampling
The method which not all members of the population have an equal chance of participating in the study
Done when a sampling frame is NOT available
Random sampling
Every member of the target population has an equal chance of being chosen
How to do RANDOM SAMPLING
- you need a sampling frame
- all the names on the list are assigned a number
- Sample is selected randomly - computer-based randomiser/ names out of a hat
Systematic sampling
When a researcher selects every nth person on the sampling frame to be a part of the sample
How to carry out SYSTEMATIC SAMPLING
- Obtain a sampling frame
- Nth number is selected by dividing the target population size by the desired sample size
- Most representative samples from this method are achieved when the sampling frame list is randomised.
Stratified sampling
The sampling frame is divided into various social groups (e.g age, gender, ethnicity etc) .
Then random sampling is used for each group to ensure the FINAL SAMPLE reflects the population in terms of representativeness
How to do STRATIFIED SAMPLING
- obtain a sampling frame
- Divide the sampling frame into social groups
- Randomly select the number of participants from each strata (group) to make it representative of the larger group
Probability sampling ADVANTAGES
No bias - more objective.
Every person in the target population has an equal chance of being selected
MORE LIKELY to be representative
Probability sampling DISADVANTAGES
Impractical: MORE time and effort- you need to obtain sampling frame, identify the sample, contact the people (SOME PARTICIPANTS MAY NOT WISH TO TAKE PART)
Not completely representative: unbiased selection does not guarantee an unbiased sample
— random selection may generate an all female sampling, making sample unrepresentative, therefore not generalisable
Opportunity sampling
A technique that involves recruiting anyone who happens to be unavailable at the time of your study.
How to carry out OPPORTUNITY Sampling
The researcher will go somewhere where they are likely to find their target population and ask people to take part.
Opportunity sampling ADVANTAGES
Simple
Quick and easy
Cheap as you are only using the first participants you find.
Opportunity sampling DISADVANTAGES
Unrepresentative: the sample is likely to be biased by excluding certain types of participants which mean they cannot confidentially generalise
E.g sample collected middle of day/ week not include students.
Volunteer sampling
When people actively volunteer to be in a study by responding to advertisement by researcher (SELF-SELECTING)
Researcher then may select those suitable for the study
How to carry out VOLUNTEER sampling
Participants self-select by responding to an advert
Volunteer sampling ADVANTAGES
Convenient and economical way to collect participants
Can reach a WIDE AUDIENCE, especially online
Volunteer sampling DISADVANTAGES
Sample bias - people with higher levels motivation/ more time may be harder to generalise.
