In Probability Sampling, what is the difference between Random, Stratified or Cluster Sampling?
Simple random sample: Every member of the population has a known and equal chance of selection
Stratified random sample: the population is divided into mutually exclusive groupie (such as age groups) and random samples are drawn from each group
Cluster (area) sample: the population is divided into mutually exclusive groups (such as blocks) and the researcher draws a sample of the groups to interview