random sampling
1. Simple random sampling
If the probability of each individual being drawn in the population is equal (that is, the sampling is random), and the composition of the population remains unchanged after an individual is drawn by sampling (that is, the independence of sampling), this sampling method is called simple random sampling.
Simple random sampling generally adopts the following three methods:
(1) draw lots. Every individual in the group is numbered and made into a label. After fully mixing, a part is randomly selected, and the individuals corresponding to this part form a sample.
(2) Look-up table method. Check the random number table to determine the number of individuals extracted from the population, and the corresponding individuals will enter the sample. The random number table can start from any number in any area and then proceed in all directions in turn.
(3) Computer-generated numbering method. A random number program is compiled by an electronic computer, which is used as the number of individuals drawn into the sample from the population.