1, the number of n individuals in the design population.
2. Write the number on the number label, put the number label in the container and stir it evenly.
3. Take a batch from it at a time, and take it n times without putting it back.
4. Take out N individuals corresponding to N numbers to obtain a sample with a capacity of N. ..
Extended data:
In life, people often draw lots to allocate tasks or prizes. It is fair to every lottery winner whether to catch first or later.
Let's assume that there are three people, A, B and C, who have made three lots, and one of them is "good". Assuming that A catches first, the probability that A catches "good" is 1/3. When B continues to grasp, whether B can catch "good" is related to whether A can catch "good".
We should consider it separately: if A catches "good", the probability of B catching good is 0. If A fails to catch "good", then the probability of this event is 2/3, and then the probability of B catching good is 1/2, that is, 1/3. Taken together, the probability of B catching a good one is 65433.
If A fails to catch "good" (the probability is 2/3), it depends on B. If B catches "good" (the probability is1/3x0+2/3x1/2 =1/3), C fails to catch it.
So it seems that the lottery is in no particular order, and everyone has equal opportunities, which is fair.
Baidu encyclopedia-lottery method