1, equidistant sampling: arrange all the units in the population in a graphic or list form according to a certain sign or order (so-called queue), and then extract the sample units at equal distance or interval.
The characteristics are: the units extracted are evenly distributed in the population, and the samples extracted can be less than pure random sampling. Equidistant sampling can be queued with signs related to the survey items or signs unrelated to the survey items.
2. Type sampling: divide the whole unit into several types or layers according to its attribute characteristics, and then randomly select sample units from the types or layers.
The characteristics are: due to classification and stratification, the similarity between various types of units increases, and it is easy to extract representative survey samples. This method is suitable for situations where the overall situation is complex, there are large differences between units and there are many units.
3. Cluster sampling: that is, sampling survey units in groups from the population, rather than sampling survey samples one by one.
The characteristics are: the investigation units are relatively concentrated, and the organization and conduct of the investigation work are more convenient. However, the distribution of survey units in the population is uneven and the accuracy is poor.
According to the sampling method, sampling survey can be divided into probability sampling and non-probability sampling. Probabilistic sampling is based on the principles of probability theory and mathematical statistics, selecting samples from the investigated population, quantitatively estimating and inferring some characteristics of the population, so that possible errors can be controlled in a probabilistic sense.
Extended data:
Sampling survey is economical, effective, adaptable and accurate to extract some individuals from the population of the research object as samples to investigate and infer the digital characteristics of the population.
Sampling survey is a statistical survey method to infer the total number of overall signs according to some actual survey results, which belongs to the category of incomplete survey. According to the scientific principle and calculation, it extracts some sample units from the population of things composed of several units for investigation and observation, and uses the obtained survey mark data to represent the population and infer the population.
Scope of application:
First, things that cannot be fully investigated. Some things are destructive when measured or tested, and it is impossible to conduct a comprehensive investigation. For example, the seismic test of TV, the durability test of light bulbs and so on.
Second, some things can be comprehensively investigated in theory, but in fact they cannot be comprehensively investigated. For example, know how many trees there are in a forest and how the family life of employees is.
Thirdly, sampling survey method can be used for quality control in industrial production.
Fourthly, by means of sampling inference, we can test a general hypothesis, judge whether it is established or not, and decide whether to accept it or not.
Baidu Encyclopedia-Sampling Survey Method