Question

A pharmaceutical company interested in measuring how often physicians prescribe a certain drug has selected a simple random sample from each of two groups: M.D. (Medical Doctors) and D.O. (Doctors of Osteopathic). What is this type of sampling called?
Simple random sampling.
Stratified random sampling.
None of the above.

Answer 1

In simple random sampling, we sample our data from the entire population. Here the effects of the subpopulations in a population are not considered.

In stratified random sampling, we sample our data from the individual subpopulations(partitions of a population) of an entire population. Sampling in this way helps in determining the effect of subpopulations.

In the above problem, they had sampled from two groups of a population(M.D and D.O). Hence such type of sampling is called stratified random sampling.