Explain stratified sampling in details.
Answer
Stratified sampling is a probability sampling technique that is distinguished by two-step procedure it involves. In first step population is divided into mutually exclusive and collectively exhaustive sub-populations that are known as strata. In second step, a simple random sample of elements is chosen independently from every strata or group. This approach is used when there is considerable diversity among population elements. Major aim of this technique is to reduce cost without lose in precision.