Research Methods- Sampling Flashcards
Population -
A group of people who are the focus of the researcher’s interest, from which a smaller sample is drawn.
Sample -
A group of people who take part in a research investigation. The sample is drawn from a (target) population and is presumed to be representative of that population, i.e. it stands ‘fairly’ for the population being studied
Sampling techniques -
The method used to select people from the population.
Bias -
In the context of sampling, when certain groups may be over or under-represented within the sample selected. For instance, there may be too many younger people or too many people of one ethnic origin in a sample. This limits the extent to which generalisations can be made to the target population.
Generalisation -
The extent to which findings and conclusions from a particular investigation can be broadly applied to the population. This is made possible if the sample of participants is representative of the population.
What is a population in research?
A population refers to the large group of individuals a researcher is interested in studying, such as students in the North West, children under six with autism, or women in their thirties.
What is a target population?
A target population is a subset of the general population that the researcher aims to study.
Why is a sample used instead of the entire population in research?
Due to practical and economic reasons, it is usually not feasible to include all members of the target population, so a smaller group (sample) is selected.
What is the goal of selecting a sample?
The goal is to select a sample that is representative of the target population to allow for generalization of findings.
Why is it difficult to achieve a perfectly representative sample?
Populations are often diverse, making it challenging to capture all characteristics in a sample, leading to some degree of bias.
What is a random sample?
A random sample is a sampling method where every member of the target population has an equal chance of being selected.
How is a random sample selected?
A complete list of the target population is made, each member is assigned a number, and a lottery method (e.g., random number generator) is used to select the sample.
What is a systematic sample?
A systematic sample involves selecting every nth member of the target population (e.g., every 5th person on a list).
How is a systematic sample created?
A sampling frame (e.g., alphabetical list) is created, and a sampling interval (e.g., every 3rd person) is applied to select participants.
What is a stratified sample?
A stratified sample reflects the proportions of sub-groups (strata) within the target population, ensuring the sample is representative.
How is a stratified sample created?
The population is divided into strata, the proportions for each stratum are calculated, and participants are randomly selected from each stratum.
What is an opportunity sample?
An opportunity sample involves selecting participants who are readily available and willing to take part in the study.
What is a volunteer sample?
A volunteer sample consists of participants who self-select to be part of the study, often through advertisements or direct requests.
What is the main strength of a random sample?
It is free from researcher bias, as the researcher has no influence over who is selected.
What is a limitation of random sampling?
It can be time-consuming and difficult to obtain a complete list of the target population, and the sample may still be unrepresentative.
What is a strength of systematic sampling?
It avoids researcher bias once the selection system is established and is usually fairly representative.
What is a strength of stratified sampling?
It produces a representative sample by reflecting the composition of the population, allowing for generalization of findings.
What is a limitation of stratified sampling?
It cannot account for all differences within the population, so complete representation is not possible.
What is a strength of opportunity sampling?
It is convenient, cost-effective, and saves time compared to other sampling methods.
What is a limitation of opportunity sampling?
It is often unrepresentative and prone to researcher bias, as the sample is drawn from a specific area or group.
What is a strength of volunteer sampling?
It is easy to collect, requiring minimal effort from the researcher.
What is a limitation of volunteer sampling?
It suffers from volunteer bias, as participants may share specific traits (e.g., helpfulness, curiosity) that affect generalizability.
What is a sampling frame?
A sampling frame is a list of individuals in the target population from which a sample is drawn.
Why might a random sample still be unrepresentative?
Random selection can still result in an unrepresentative sample due to chance, and selected participants may refuse to participate.
What is volunteer bias?
Volunteer bias occurs when participants who self-select share specific characteristics, potentially skewing the results.
What is researcher bias in sampling?
Researcher bias occurs when the researcher influences participant selection, such as choosing individuals they think will support their hypothesis.
Why is generalizability important in research?
Generalizability allows researchers to apply findings from the sample to the broader target population, increasing the study’s relevance.
What is an example of an opportunity sample?
A researcher standing on a street and asking passersby to participate in a study is an example of opportunity sampling.
What is an example of a stratified sample?
In a study of football fans in Manchester, a stratified sample might include 40% Manchester United fans, 40% Manchester City fans, 15% Bolton fans, and 5% Leeds fans, reflecting the population proportions.
What is an example of a volunteer sample?
Placing an advertisement in a newspaper or on a notice board and selecting participants who respond is an example of volunteer sampling.
