The concept of simple random sampling
Generally speaking, assuming that a population contains n individuals, if a sample is extracted from it one by one, and the probability of each individual being extracted is equal, then such a sampling method is called simple random sampling.
Simple random sampling requires that the total number of samples sampled, n, is limited.
The numb n of simple random samples is less than or equal to that numb n of the sample population.
Extract simple random samples from the population one by one.
Simple random sampling is a kind of sampling that cannot be put back.
The probability of each individual being systematically sampled is n/n.