[b]uRandom sampling[/u]/b

A bsimple random sample/b is one where every member of the population has an equal chance of being selected for the sample. This might be achieved by assigning every member of the population a number and using a random number generator to select the members of the sample.

In bsystematic sampling/b, the members of the sample are chosen at regular internals from an ordered list.

In bstratified sampling/b, the population is divided into groups, and a random sample is selected from each.

[b]uNon-random sampling[/u]/b

In bquota sampling/b, a sample is selected which reflects the characteristics of the whole population.

In bopportunistic sampling/b, the sample is taken from members of the population who happen to be available at the time and fit the required criteria.