A.？ draw lots
B.？ Direct extraction method
C.？ Random number table method
D.？ Equidistant random sampling
First, the characteristics of simple random sampling
1. When a sample with a capacity of n is extracted from a population containing n individuals by simple random sampling, the probability of extracting one individual at a time is: the probability of each individual being extracted in the whole sampling process is:
2. Simple random sampling is characterized by sampling one by one, and the probability of each individual being drawn is equal;
3. Simple random sampling method embodies the objectivity and fairness of sampling and is the basis of other more complex sampling methods.
4. Simple random sampling is not put back sampling; Is extracted one by one; This is an equal probability sampling.
Second, the common methods of simple sampling
1, lottery method: firstly, all individuals in the population are numbered (* * * n) (the range of numbering can be 1 to n), and the numbers are written on numbers with the same shape and size (numbers can be balls, cards, paper strips, etc. ), then put these numbers in the same box, stir them evenly, and draw them from each time in the lottery.
2, random number table method: random number table sampling "three steps": the first step, number the individuals in the population; Step 2, select the starting number; Step 3, obtain the sample number probability:
Third, the 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.
1. Generally speaking, suppose a population contains n individuals, from which n individuals are selected as samples (n≤N). This sampling method is called simple random sampling if the probability of each individual in the group being drawn is equal every time.
2. There are two simplest random sampling methods: the lottery method and the random number table method.
3. Samples with a capacity of n are extracted from individuals with a population of n, and the probability of each individual being extracted is.