What is a Representative Sampling?

Also called sampling. Take a part of the sample unit from all the samples to be studied. The basic requirement is to ensure that the sample units drawn are fully representative of all samples. The purpose of sampling is to estimate and infer the characteristics of all samples from the analysis and research results of the sampled units. It is a cost-effective work and research method commonly used in scientific experiments, quality inspection and social surveys.

(1) Simple random sampling

Generally, let N be the number of a population.

(1) Define the population

Defining the population is to clearly define the overall scope and boundary of the sample drawn from the total before the specific sampling.

(2) Develop a sampling frame

The task of this step is to collect the list of all sampling units in the population based on the clearly defined overall scope, and establish a sampling frame for sampling by uniformly numbering the list.

(3) Decide on a sampling plan

(4) Actual samples

The actual work of taking samples is based on the above steps, and in strict accordance with the selected sampling plan, select each sampling unit from the sampling frame to form a sample.

(5) Evaluate the quality of the sample

The so-called sample evaluation refers to the preliminary inspection and measurement of the quality, representativeness, deviation, etc. of the sample, and the purpose is to prevent errors caused by excessive deviation of the sample ^[3]

There are four principles to be followed in the sampling design process:

(1) the purpose;

(2) Testability;

(3) feasibility;

(4) Economic principle.