The characteristics of sampling survey are as follows

The characteristics of sampling survey are: economy (the most obvious advantage), strong timeliness, wide adaptability and high accuracy.

Sampling survey is the most commonly used survey method. It refers to extracting some units from the population according to certain principles and procedures, and obtaining information by investigating these units, so as to understand the overall situation or estimate the relevant parameters of the population.

Classification of sampling survey:?

1, simple random sampling method

This is the simplest one-step sampling method, which selects the sampling unit from the population, and every possible sample extracted from the population has the same probability of being extracted. When sampling, the sampling units in the sampling population are arranged into 1 ~ n codes, and then the random numbers between 1 ~ n are determined by a random number table or a special computer program, and those units that match the random numbers in the population become random sampling samples.

This sampling method is simple and easy for error analysis, but it needs a large sample size and is suitable for small differences between individuals.

2. Systematic sampling method

This method, also known as sequential sampling, randomly selects samples from the population at certain intervals (that is, "every few times"). The advantages of this method are good sample distribution, good theory and easy calculation of the overall estimate.

3. Stratified sampling method

According to some specific characteristics, it divides the population into several homogeneous and non-overlapping layers, and then samples independently from each layer, which is an unequal probability sampling. Stratified sampling uses auxiliary information to stratify, each layer should be homogeneous and the difference between layers should be as large as possible.

Such stratified sampling can improve the representativeness of samples, the accuracy of overall estimation and the efficiency of sampling scheme, and the operation and management of sampling are more convenient. But the sampling frame is more complicated, the cost is higher and the error analysis is more complicated. This method is suitable for cases with complex matrix, great differences among individuals and large numbers.

4. Cluster sampling method

Cluster sampling is to group the whole unit first, which can be grouped naturally or as needed. In the traffic survey, we can group according to regional characteristics, randomly select groups as sampling samples, and investigate all units in the sample group. Cluster sampling samples are relatively concentrated, which can reduce the investigation cost.

For example, in the survey of residents' travel, this method can be used to group residents according to different living areas, and then randomly select the groups as samples. The advantage of this method is simple organization, but the disadvantage is poor sample representativeness.