Question

There are several types of sampling strategies. These include: simple random sampling, systematic random sampling, stratified random sampling (stratified proportionately of disproportionately). What are the primary characteristics that distinguish these approaches? And, conversely, what characteristic makes each of these approaches similar?

Answer 1

The main distinguish characteristic is how sample is gathered, how each unit of sample is chosen.
Main similar characteristic is all samples are supposed to have enough units quantities