Define population
The group of people of interest to the researchers, from which a sample is typically drawn
Define sample
A subset or small proportion of the population
What is sampling?
The process of choosing members of a population of interest to be included in a sample that is studied
What is External Validity?
The degree to which study results, based on a sample, may be generalized to the population from which the sample was drawn or other populations
What is a sampling frame?
The individuals or clusters of individuals in a population who might actually be selected for inclusion in the sample
What is a “response rate”
The percentage of people selected for a sample who actually complete a survey
What is probability sampling?
A type of sampling procedure in which one is able to specify the probability that any member of the population will be included in the sample
What is non-probability sampling?
A type of sampling procedure in which one cannot specify, or does not know, the probability that any member of the population will be included in the sample (can also be known as non-random sampling)
What is simple random sampling?
A sampling procedure in which each member of the population has an equal probability of being included in the sample
What is a random sample
When everyone in a given population is equally likely to have been selected to participate in the study
What is stratified random sampling?
A sampling procedure in which the population is divided into strata (subgroups) followed by random sampling from each stratum
What is cluster sampling?
A method of sampling in which clusters of individuals are identified. Clusters are sampled, and then all individuals in each cluster are included in the sample
What is convenience sampling?
A type of non-probability sampling that involves selecting participants in a haphazard manner, usually on the basis of availability, and without regard for the representatives of the sample
What is purposive sampling?
A type of convenience sampling procedure conducted to obtain predetermined types of individuals for the sample
What is quota sampling?
A sampling procedure in which the sample is chosen to reflect the numerical composition of various subgroups in the population. A convenience sampling technique is used to obtain the sample
What is a confidence interval?
Serves as a range of plausible values that are likely observed if the study were to be repeated. Wider confidence intervals indicate greater uncertainty
What is sampling error?
The degree to which the estimate based on a sample deviates from the true population value, also called margin of error
What is statistical power?
The probability of correctly rejecting the null hypothesis using a particular statistical test
What is the difference between population and sample?
A population refers to every single individual within a group of interest of researchers, and a sample is typically a small group of people drawn from it
When could we study a population directly?
The population is small, easily accessible, and has guaranteed 100% participation
When must we study samples instead of populations
When the population is too large or inaccessible (most likely)
What are some advantages of having a larger sample size? Why does having a larger sample provide these advantages?
Advantages:
- improves accuracy to the population
- Reduces influence of outliers
- enhances generalizability
- decreases margin or error
- minimizes sampling variability
Larger sample means more of the population is being tested, therefore making results more generalizable
What is the difference between probability sampling and non-probability sampling? Which form is more common?
Probability sampling allows results to be generalized to the population, while non-probability sampling cannot be
Non-Probability sampling is more common as it’s cheap and convenient
What’re some advantages of probability and non-probability sampling?
Probability Sampling:
- Representative of the population
- Does not always have to sample from multiple lists of people for random sampling (cluster only)
Non-Probability Sampling:
- Inexpensive
- Efficient
- Convenient
