sampling & research design Flashcards
population
The entire set of individuals (or units) of interest.
target population
The specific population to which you want to generalize.
sample
The subset of the target population actually studied
probability sampling
Every individual in the population has a known, nonzero chance of being selected
(e.g., simple random sampling, systematic sampling, stratified sampling).
nonprobability sampling
The likelihood of selection is not known (e.g., convenience sampling, self-
selection, snowball sampling)
sampling frame
The list or mechanism from which a sample is actually drawn
selection interval / systematic sampling
a fixed interval used to select participants from a list (e.g., every 7th name).
What is the difference between a population, a target population, and a sample?
population -> target population -> sample
advantages or disadvantages of probability sampling
Advantages:
Minimizes Bias
Generalizability
Statistical Accuracy
Reproducibility
Disadvantages:
Time-Consuming
Expensive
Difficult to Implement
advantages or disadvantages of nonprobability sampling
Advantages:
Quick and Cost-Effective
Useful for Exploratory Research
Practical for Hard-to-Reach Groups
Disadvantages:
Higher Risk of Bias
Limited Generalizability
Lack of Statistical Accuracy
how is selection interval determined
by choosing a specific range within a dataset based on factors like the desired sample size, distribution of data, and the research question
why is having a complete or accurate sampling frame important
for reducing sampling error?
it ensures that every member of the population has an equal chance of being selected for the sample
quantitative methods
○ Result in data that can be represented by and condensed into numbers
Less depth, more breadth, focusing on a larger number of cases
ex. survey
qualitative methods
○ Ways of collecting data that yield results such as words or text
○ Gain in-depth understanding of a relatively small number of cases
Potential for greater richness in meaning than quantified data
mixed method
○ They are complementary
○ Researchers may prefer one because they’re trained in one or favor one
units of analysis
- A person, collective, or object that we want to learn more about
- This encompasses a larger population that we are interested in making claims about
margin of sampling error
Describes how close we can reasonably expect a survey result (sample statistic) to fall relative to the true population value (parameter)
sampling error
- The difference between the statistics obtains from a sample and the actual parameters of a population
- Probability sampling allows for the calculation of the sampling error that is expected given the size of the sample being used
Because surveys only select a sample of the population, the result probably won’t exactly match the ‘true’ result that we would get if we interviewed everyone in the population
- Probability sampling allows for the calculation of the sampling error that is expected given the size of the sample being used
simple random sampling
A sampling technique where the researcher gives all members of a population (more accurately, of a sampling frame) an equal probability of being selected
, systematic sampling
- Systematically choosing sampling units from a list by defining an interval (k) and then selecting every kth element in our list
A probability sampling method in which a random sample from a larger population is selected
stratified sampling
- A sampling technique where researchers divide the study population into two or more mutually exclusive subgroups (strata) and then draw a sample from each subgroup
- Used to ensure that the sample adequately represents the identified subgroups
To make sure that a small subgroup is adequately represented in our sample
- Used to ensure that the sample adequately represents the identified subgroups
Proportionate stratified sampling
Carve up our sampling frame into strata then choose cases from each stratum in line with its numbers in the larger population
disProportionate stratified sampling
An approach to stratified sampling in which the sizes of the subgroup samples do not match their relative sizes within the population
oversampling
When a subgroup represents a greater share of a sample than the same subgroup represents in the larger population