Random Sampling – a sampling technique where each sample of its size has an equal chance of being selected.
Stratified Sampling – a sampling technique whereby the population is divided into strata according to given criteria and the sample that is chosen preserves the strata proportions.
Systematic Sampling – a sampling technique where the sampling starting point is chosen randomly and the rest of the sample is chosen periodically thereafter.
Quota Sampling – similar to stratified sampling but researchers may select the units they require from the given strata.
Opportunity Sampling – is obtained when members from a given population are willing to participate in the investigation, such as a survey.