1. Simple random sampling requires that the total number of samples sampled n 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 sampling probability of each individual sampled systematically is n/n. ..
Sampling method:
Direct sampling method, that is, direct random sampling from the population. For example, a number of goods are randomly selected from the shelves for inspection; Choose several stalls from the farmer's market stalls for investigation or visit.
Draw lots: firstly, number all individuals in the population (the range of numbers can be 1 to n), and write the numbers on numbers with the same shape and size, which can be balls, cards, paper strips, etc. Then put these numbers in the same box and mix them evenly.
When drawing lots, every time 1 number is drawn, a sample with a capacity of is obtained. When numbering individuals, you can also use the existing number, for example, when taking samples from the whole class, you can use the student's student number and seat number. The lottery method is simple and easy, and it is suitable for the situation that there are not many individuals in the whole population.
Random number table method: random number table method, that is, using random number table as sampling tool. Random number table (see example), also known as random number table, randomly arranges 10 numbers from 0 to 9 into a table for future reference.