(1) Simple random sampling requires that the total number of samples n to be sampled is limited.
(2) The number n of simple random samples is less than or equal to the number n of the sample population.
(3) Extract simple random samples from the population one by one.
(4) Simple random sampling is a kind of sampling that cannot be put back.
(5) The probability of each individual being systematically sampled is n/n. ..
limit
1. It is time-consuming and laborious to number the research objects in advance, and it is easy to waste resources.
2. The overall distribution is scattered, which will make the distribution of sampling samples scattered and bring difficulties to research.
3. When the sample size is small, there may be deviation, which will affect the representativeness of the sample.
4. When it is known that a certain characteristic of the research object will directly affect the research results, if we want to control it, we can't use simple random sampling method.