Sampling Flashcards
How is RANDOM sampling conducted?
- Every person in the sampling frame has an equal chance of being randomly selected for the sample.
- Small number of people = picked out of a hat.
- Large number of people = a computer programme can generate a list of random numbers, then are matched up with the names and addresses on the researcher’s population list.
What are advantages of RANDOM sampling and why is it used?
It is used so that there is a fair sample which will represent the wider population. Everyone has an equal chance.
What are limitations of RANDOM sampling?
Can lead to a bias sample (a small chance). For example, in terms of age, there may be too many people the same age.
How is STRATIFIED sampling conducted?
- When the sampling frame is ‘divided’ into strata (sub-categories) that the researcher is interested in, such as gender, age, class and ethnicity, and then a certain number of people are randomly selected from each of these sub-categories, often in proportion to their representation in the population.
- E.g. If A Level students represent only 20% of all students at college, then 20% of those A Level students will be chosen randomly from this stratum to be a part of the sample.
What are advantages of STRATIFIED sampling and why is it used?
Reduces sampling bias → it assures that all subgroups of the population are proportionally represented in the sample.
What are limitations of STRATIFIED sampling?
Time-consuming to set up → time-consuming to organise and calculate the different sampling frames.
How is QUOTA sampling conducted?
- Like stratified sampling, it divides the target population into subgroups (e.g. by sex, age, social class or ethnicity) and the researcher is given a quota (a certain amount needed to sample) that they need to reach.
- E.g. The researcher may need to find 30 women between the ages of 25 + 35 to answer a questionnaire on magazine readership. The first 30 women of the correct age will have filled the quota.
What are advantages of QUOTA sampling and why is it used?
Less time-consuming and less expensive as no sampling frame is needed.
What are limitations of QUOTA sampling?
Can lead to a biased sample → it may not be representative as the researcher’s own judgement can lead to bias + will result in distorted quota.
How is SNOWBALLING sampling conducted?
- Used when it is difficult or impossible to obtain a sample of people to research on.
- It is often used when the research is highly sensitive or deals with secretive or deviant groups (e.g. criminals, sexual deviants, drug users or religious cults) as individuals may not be identified.
- The researcher will attempt to make contact with a particular existing person or group to be studied.
- The researcher then asks the participant to recommend another person who fits the sample criteria, and so on until they have built up a number of contacts.
What are advantages of SNOWBALLING sampling and why is it used?
Deep insight → provides valuable insight into social groups that would have been difficult to obtain using a sample frame.
What are limitations of SNOWBALLING sampling?
- Unrepresentative → it relies on a very small network of people who have come through recommendations.
- This makes the research findings to find difficult to evaluate.
- Participants’ information may be biased or incorrect, which makes it difficult to assess, so there is no way of knowing whether the sample is representative of the population or not.
How is OPPORTUNITY sampling conducted?
When researchers themselves approach anyone who is available and willing to participate. E.g. This can be asking passers-by in the street or a shopping mall.
What are advantages of OPPORTUNITY sampling?
Quick and practical.
What are limitations of OPPORTUNITY sampling?
Prone to bias → sample may be unrepresentative of your target population and therefore it will be hard to make generalisations from the research findings.
