Convenience sample
individuals in the sample are obtained by âproximityâ to the researcher
Voluntary sample
individuals have the choice to be included in the sample
Simple random sample (SRS)
each member of the population has an equal chance of being chosen for the sample
Stratified random sample
the population is separated into groups (strata) and an SRS is collected for each of the strata
Cluster sample
the population is separated into groups (clusters) and a RNG is used to select clusters where every individual in that cluster is sampled
Systematic random sample
A RNG is used to select a random individual (starting point) in the population and every nth individual is selected afterwards
Undercoverage
some people are less likely to be chosen
Nonresponse
people canât be reached or refuse to answer
Response bias
problems in the data gathering instrument/process