Answer:
The answer is representative sampling.
Step-by-step explanation:
A representative sample is a small group that is used to represent a larger population. For the results to be reliable, the sample must accurately reflect the larger population. E.g. in a school with 400 women and 300 men, an ideal sample would include 40 females and 30 males.
The greatest advantage is that it's less expensive and time consuming than sampling the entire population. However, obtaining a truly representative sample may be difficult.