Sampling Flashcards
What is a sample?
A sample is a group of people that represent a certain type / doesn’t have to be people tho.
What is Sampling bias?
the sample used in a study or survey is not representative of the larger population it’s supposed to represent.
This can happen if certain groups or individuals are systematically overrepresented or underrepresented in the sample, leading to inaccurate or misleading results.
What is a representive sample?
accurately reflects the characteristics of the larger population from which it is drawn.
How to achieve representative sample ?
researchers use various sampling techniques to ensure that every subgroup within the population has a fair chance of being included in the sample.
helps to minimize sampling bias and ensures that the findings from the sample can be generalized to the broader population with greater confidence.
Can a sample literally represent a population?
What is epsem?
An equal probability selection method (epsem) is a procedure for producing a sample into which every case in the target population has an equal probability of being selected
What is Randomness?
process of selecting individuals or items from a population in a way that every member of the population has an equal chance of being chosen.
Why is random sampling good?
helps ensure that the sample is representative and minimizes bias
-Randomness helps to ensure the generalizability of the findings from the sample to the larger population.
How can random sampling be achieved?
random sampling - where each member of the population has an equal probability of being selected
stratified random sampling - where the population is divided into subgroups and random samples are taken from each subgroup.
What is random sampling? - simple
where each member of the population has an equal probability of being selected
What is stratified random sampling?
where the population is divided into subgroups and random samples are taken from each subgroup.
What us Opportunity Sample?
Sometimes called a convenience or haphazard sample.
-type of non-probability sampling method where the researcher selects individuals or items for inclusion in the sample based on their availability and accessibility (easily recruitable)
Problems with opportunity sample?
-Can introduce bias because it may not accurately represent the larger population.
-results obtained from an opportunity sample may not be generalizable to the broader population due to the potential for sampling bias.
What is snowball sample?
Where the people initially recruited for the sample in turn recruit other participants.
how snowball sampling can be better than convenience sampling:
-Access to hard-to-reach populations: Snowball sampling allows researchers to access populations that are difficult to reach through traditional means. Participants recruited through referrals may be more willing to participate and provide valuable insights.
-Network effects: Snowball sampling leverages existing social networks, which can lead to a more diverse sample compared to convenience sampling. This can be especially advantageous when studying social phenomena or behaviors influenced by social networks.
Does snow ball sample have EPSEM?
snowball sampling does not have EPSEM
-The probability of being selected for the sample depends on an individual’s connection to existing participants and their willingness to participate in the study.
-non-probability sampling method.
What is EPSEM
Equal Probability of Selection Method)
EPSEM refers to sampling methods where each unit in the population has an equal probability of being selected for the sample.
What is Self-selecting Sample?
-non-probability sampling method where individuals choose themselves to participate in a study - typically in response to some form of invitation or recruitment effort.
When are self reporting samples used?
in situations where it’s difficult to reach a specific population or when individuals with particular characteristics are sought after for a study. Common examples include online surveys, where participants voluntarily respond to invitations to participate, or support groups, where individuals with specific experiences or interests self-select to join.
Problems with self report sample?
While convenient and efficient, they often suffer from selection bias because the individuals who choose to participate may differ systematically from those who do not.
- findings from self-selecting samples may not be generalizable to the broader population, and caution should be exercised when interpreting results obtained from this sampling method.
Sampling error
Opportunity sampling advantage
-easy
-natural experiments
Opportunity sampling disadvantages
- Unlikely to provide a representative sample
- Highly dependent on individual researcher
systematic sampling
probability sampling method where researchers select members of the population at a regular interval - for example, by selecting every nth person on a list of the population.
Systematic sampling advantages
-unbiased selection
-generalisation
systematic sampling disadvantages
Sampling frame should be random
It can introduce bias
quota sampling
non-probability sampling where researchers will form a sample of individuals who are representative and have interest in study
Quota sampling disadvantage
potential for selection bias, which can result in a sample that is unrepresentative of the population
ncreases the risk of researcher bias as a researcher might include people in research who he finds to easy to approach or have co-operative nature
Self-selected sampling
A sampling method made up of volunteers
Self-selected sampling advantages
cheap
easy
Self-selected sampling disadvantages
bias
unreprestentative
snowball sampling advantages
chain referral process allows the researcher to reach populations that are difficult to sample when using other sampling methods.
The process is cheap, simple and cost-efficient.
This sampling technique needs little planning
snowball sampling disadvantages
Representativeness of the sample is not guaranteed. The researcher has no idea of the true distribution of the population and of the sample.
Sampling bias is also a fear of researchers when using this sampling technique. Initial subjects tend to nominate people that they know well.
Event sampling
the observer records all instances of a particular behavior during a specified time period
time sampling
a measurement of the presence or absence of behavior within specific time intervals
Target pop.
the total group of individuals from which the sample might be drawn.
Sampling. Frame
list or other device used to define a researcher’s population of interest. The sampling frame defines a set of elements from which a researcher can select a sample of the target population
Advantages of random sampling
simplicity and lack of bias.
make generalizations about a population.
disadvantages of random sampling
difficulty gaining access to a list of a larger population
