Systematic sampling&Stratified random sampling有什麼分別?

Systematic sampling is often used instead of random sampling. It is also called an Nth name selection technique. After the required sample size has been calculated, every Nth record is selected from a list of population members. Systematic sampling is frequently used to select a specified number of records from a computer file.
In Stratified sampling . First, researcher first identifies the relevant stratums and their actual representation in the population. A stratum is a subset of the population that share at least one common characteristic. Examples of stratums might be males and females, or managers and non-managers. The Random sampling is then used to select a sufficient number of subjects from each stratum. Stratified sampling is often used when one or more of the stratums in the population have a low incidence relative to the other stratums.
Differences:
Stratif ied random sampling needs to divided the population into different stratums but Systematic sampling dose not.
Systematic sampling only make one random sampling from the population but Stratif ied random sampling make random samplings in each stratums.