"Census and Sample Survey" PPT courseware

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"Census and Sample Survey" PPT courseware

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In social production and real life, to make scientific and reasonable judgments and decisions on certain issues, it is usually necessary to first collect some relevant data through surveys, and then conduct analysis and research.

From 1984 to 1996, my country conducted a large-scale current survey on land use across the country. For this survey, 500,000 professionals were organized across the country, using remote sensing data mainly based on aviation, and using full field field survey methods to find out the accurate land data of each plot and obtain comprehensive information.

Like this, a comprehensive survey of all inspection objects for a specific purpose is called a survey. The totality of objects under investigation is called a population, and each object under investigation that makes up the population is called an individual.

In the above census, the national land use area is the overall area, and the area of ​​each plot is individual.

Can you give practical examples of census-based surveys?

Using censuses, accurate and comprehensive data can be obtained by investigating every individual relevant to the problem. However, for many problems it is not necessary or even possible to obtain all the data relevant to the problem.

Analyze the following three practical issues:

(1) A certain department wants to investigate the weekly extracurricular activity time of seventh grade students in the province;

(2) The quality supervision department should test the wear resistance of a certain brand of composite wood flooring;

(3) The river affairs department needs to know the sediment content of the Yellow River water flowing through a certain hydrological station in July.

There are a large number of students in question (1). If a census method is used to survey the weekly extracurricular activities of every seventh grade student in the province, not only will the scope of the survey be wide, but it will also take a long time and consume a lot of manpower and material resources. Large, and the results of such surveys do not require exact values;

Question (2) uses a census method to measure the wear resistance of wooden boards, which requires experiments on every wooden floor of the brand, and such experiments are destructive;

In question (3), it is impossible to seal all the Yellow River water flowing through the area in July, then allow the sediment to settle, and then measure the quality of the sediment. Therefore, questions (1)(2)(3) cannot collect data through census.

Think about it, if you were asked to investigate questions (1) (2) (3), how would you collect data?

Discuss:

When do you think it is necessary to use a census to obtain data, and when to use a sample survey to obtain data?

·When a comprehensive understanding of the data is required and the overall number is small, a census is used.

·When the population is large or limited by objective conditions or the investigation is destructive, sampling surveys are used.

Example 2. Are the following surveys a census or a sample survey? If this is a census, indicate the population and individuals. If it is a sample survey, please indicate the population, individual, sample and sample size.

(1) Select 5 washing machines from a batch and investigate the service life of this batch of washing machines.

Solution: This survey is a sampling survey.

Overall: The longevity of this batch of washing machines.

Individual: The service life of each washing machine in this batch.

Sample: the service life of 5 washing machines selected from it.

Sample size: 5.

Summarize

The concepts of population, individual, sample and sample size:

Overall The entirety of the objects to be examined.

Individual: Each object of investigation that makes up the whole.

Sample A portion of individuals selected from the population.

Sample size The number of individuals in the sample.

Note: Only in sample surveys, there are samples and sample sizes.

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"Census and Sampling Survey" PPT courseware 3:

"Census and Sample Survey" PPT Courseware 3 Learning Objectives 1. Understand the significance of census and sample survey, and be able to distinguish between census and sample survey in specific situations. 2. Be able to describe the characteristics of census and sampling surveys, and understand the necessity of sampling. 3. Understand the overall, individual,...

"Census and Sampling Survey" PPT Courseware 2:

"Census and Sample Survey" PPT Courseware 2 Objective Tips Learning objectives: 1. Understand and be able to distinguish between census and sample survey in specific situations; 2. Be able to describe the characteristics of census and sample survey, and understand the necessity of sampling; 3. Understand Population, individual, sample and sample..

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Update Time: 2024-11-03

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