What are the probability sampling methods commonly used in community health service survey?

1. Simple random sampling is to extract a part of observation units in the population by completely random method to form a sample (that is, the probability that each observation unit is selected into the sample is the same). The common method is to number all the observation units in the population first, and then draw some observation units from them to form samples by lottery, random number table or computer-generated random number.

2. Systematic sampling is also called equidistant sampling or mechanical sampling, that is, all individuals in the group are sorted and numbered according to the characteristics unrelated to the research phenomenon. Then, according to the sample content, the sampling interval k is specified. Randomly select i(i3, cluster sampling is to divide the population into k groups, each group contains several observation units, and then randomly select K group (k4). Stratified sampling is to divide all individuals in the population into several layers according to some characteristics that have great influence on the main research indicators, and then randomly select a certain number of observation units from each layer to form samples. For example, to sample the current situation of health services in a province, because of the great difference between urban and rural health services, it can be divided into two levels: urban and rural, and then a certain number of observation units are randomly selected from urban and rural areas to form samples.