In this analysis, I have an in-depth understanding of sampling methods, flexible use and analysis of examples in their lives. In equal probability cluster sampling, there are unbiased estimation method and ratio estimation method. The latter has two methods: ratio estimation method with cluster size as auxiliary variable and ratio estimation method with independent variable as auxiliary variable. In order to distinguish There are two very confusing overall estimation methods: ratio estimation and unbiased estimation. The distinction between the two is based on the number of sampling units. Only the population based on the average of the number of sampling units is an unbiased estimate, and the population based on the sample values calculated based on the other flag values of the sampling units is Ratio estimation.