Chapter 1.2

three methods of random sampling

simple random sampling, systematic sampling, stratified sampling.

advantage of stratified sampling

the sample accurately reflects the population structure

disadvantage of stratified sampling

population must be clearly stratified into distinct strata

advantage of systematic sampling

simple and quick to use, suitable for large populations and samples

disadvantage of systematic sampling

sampling frame is required. may be biased

advantages of simple random sampling

not biased. suitable for small populations and samples. each sample has an equal chance of being selected.

disadvantage of simple random sampling

sampling frame is required. not suitable for large populations and samples.

simple random sampling

every sample of a population has an equal chance of being selected.

stratified sampling

population is divided into groupds and a random sample is taken from each group that the sample reflects the group as a whole.

systematic sampling

individuals are chosen at regular intervals from an ordered list. the first individual is chosen at random and the rest are chosen at regular intervals.

how does simple random sampling work?

it uses a sampling frame and every person is allocated a number and a selection of these numbers is chosen at random.