(1) lottery method: firstly, all individuals in the group (there are n individuals in the group) are numbered (the range of numbering can be 1 to n), and the numbers are written on numbers with the same shape and size (the numbers can be balls, cards, paper strips, etc. ), and then put these numbers in the same box and mix them evenly, every time you draw a lottery.
(2) Random number table method: random number table sampling "three steps": the first step is to number the individuals in the group; Step 2, select the starting number; The third step is to obtain the probability of the number of samples.
Definition of simple random sampling
Generally speaking, it is assumed that a population contains n individuals, from which n individuals are extracted one by one (n≤N). If every individual in the group has the same chance to be drawn, this sampling method is called simple random sampling.