Sampling methods Flashcards
Sampling
The process or technique of selecting a suitable section of your target population. Techniques can be representative or unrepresentative; random or non-random
Sampling Frame
A list of all the members of the target population. From the list, the participants are picked, e.g. electoral register, Facebook membership, patient files, street map.
Target population
The group that the researcher wants to be able to draw a conclusion about, once the study is completed. It is from the target population that the sample to be studied is drawn. Any conclusions drawn from data collected about the sample can only be generalised to the population the sample came from
Opportunity sampling
Known as convenience sampling. The sample is made up of those who are readily available, willing to take part and suitable for the aim of the research. May not be representative. Useful for students who lack time and resources.
Purposive sampling
Setting out to find people with characteristics that are relevant to the purpose of the study. Will not be representative. Useful when a researcher has limited time and/or there is no sampling frame available. Saves time approaching those who are unsuitable.
Quota sampling
The researcher calculates how many people from each group are required and approaches people to match the characteristics until the ‘quota’ is filled. Similar to stratified sampling but doesn’t require a sampling frame. Useful for market research. Useful for collecting data in public places. May not be representative.
random sampling
Known as simple random sampling. Each member of the target population has exactly the same chance of being picked. Like numbers picked in a lottery. Fair and can be representative but not always representative, e.g. disproportionate male or female number. A sampling frame is needed.
snowball sampling
A non-random sampling technique which relies on a gatekeeper to gain access to a group and then the gatekeeper introduces the researcher to another person and from there the snowball starts to roll and get bigger. Unlikely to be representative. Useful for difficult to reach groups and for those who wish to avoid attention
stratified sampling
Dividing the population and then selecting your sample. This ensures the correct proportions are selected, e.g. male and female. A sampling frame with extra information is required to include the population’s characteristics. Useful when relevant information is known about the group e.g. age, gender etc.
systematic sampling
Known as systematic random sampling. Involves having a methodical approach to selecting participants, e.g. every 10th name on a list; or every 5th house in the street. Not everyone has an equal chance of being selected so it is not random, but seen as a fair way of proceeding. A sampling frame is needed, so useful for groups with a sampling frame. Willmott & Young chose the 38th name in the telephone directory
Volunteer sampling
A self-selecting sampling technique, which involves inviting people to volunteer for the research. An example of opportunity or purposive sampling. Useful in the absence of a sampling frame. Useful for students and for online research.
Representative sampling
A group that have the same characteristics as the population as a whole. If your sample is typical, i.e. representative, then you can generalise your results.
