Sampling methods Flashcards
What is the target population?
The group of individuals that the researcher is interested in studying.
Why are samples needed?
As it is not possible to include all members of the target population in a study, the researcher selects a smaller group - the sample
What is a sample?
Ideally, the sample will be the representative of the target population so that the findings of the study can be generalised to the rest of the target population.
What is the difficulty with samples?
It is often very difficult to represent populations in a small sample due to their diverse nature. This means that most samples contain some degree of bias.
What are the 5 sampling methods?
- Opportunity sampling
- Volunteer/Self-select sampling
- Random sampling
- Systematic sampling
- Stratified sampling
What is opportunity sampling?
Selecting anyone who happens to be willing and available.
The researcher takes the chance/opportunity to ask whoever is around at the time of the study.
What are the pros of opportunity sampling?
It is convenient. It save the researcher lots of effort, time and money compared to other methods.
What is a con of opportunity sampling?
It suffers from 2 biases.
- The sample will not be representative as they are selected from a specific place and time and therefore findings cannot be generalised.
- The researcher has total control of who they pick and can manipulate the choice of participant ( researcher bias)
What is volunteer/self-select sampling?
Participants select themselves to be part of the sample in response to an advert.
What are the pros of volunteer/self-select sampling?
It is easy, requires minimal input from the researcher and is less time consuming than other methods.
What is the cons of volunteer/self-select sampling?
Volunteer bias. Generally only helpful, keen, curious and confident people volunteer which prevents generalisation to anyone without those characteristics.
What is random sampling?
All members of the target population have an equal chance of being selected.
How do you select a random sample?
- Obtain a complete list of all members of the target population
- All names on the list are assigned a number
- The sample is generated using some sort of lottery method eg. random no. generator or names from a hat)
What are the pros of random sampling?
It is free from researcher bias. They have no influence over who they choose and this prevents them from selecting people they think would support their hypothesis.
What are the cons of random sampling?
Difficult and time-consuming. A complete list of the target population can be difficult to obtain. You could also still end up with a biased sample that is unrepresentative. Some participants may refuse to take part.
