Why results of census survey is considered better as compared to that of sample survey?

I think they key is in Peter Ellis' answer: "attempted". When you do sampling properly, you sweat the details of non-response, figure out strata and seek them out, etc. When you decide to do a census, it's easy to ignore those issues, since you're getting "everyone". Problem is, you're probably not getting everyone, but you're not thinking about who you're not actually getting.

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Sampling Method
Census method and its advantages
Sampling method and its advantages
Difference between Census and Sampling Method

There are also statistical issues with extremely large samples (as a proportion of the sampled population). I'm not sophisticated enough to understand them, but at a minimum you have problems with variance calculations. (Packages like R's survey compensate for such things in large subpopulations of a survey, and that's where I first learned about this.)

As a secondary issue, if non-sample error includes issues due to quality control at various steps in the process, having enormously more data (census) would make it much harder to have the level of quality control that you would have (with the same resources) on a smaller set of data (sample).

Imagine if you had the resources (financial and personnel) that the US Census Bureau used for a census, but you were only doing a survey of 1,000 random adults. I think you'd have much better quality control and much better analysis of the issues involved and of the data itself.

This page is part of Statistics 4 beginners, a section in Statistics Explained where statistical indicators and concepts are explained in an simple way to make the world of statistics a bit easier both for pupils and students as well as for all those with an interest in statistics.

In order to find out more about the characteristics of a group of people, households, enterprises etc., one can either conduct a census or a sample survey. In a census, data about all individual units (e.g. people or households) are collected in the population. In a survey, data are only collected for a sub-part of the population; this part is called a sample. These data are then used to estimate the characteristics of the whole population. In this case, it has to be ensured that the sample is representative of the population in question. For example, the proportion of people below the age of 18 or the proportion of women and men in the selected sample of households has to reflect the reality in the total population.

A database containing information on a complete group of units is called a register. A register needs to be updated continuously. One example is a register containing information about all businesses in a country; this is called a business register. It contains information on the name, address, employment, turnover, ownership etc. of the businesses in the country. Such a register can then be used as the basis for a census or for the selection of a representative sample for a survey.

A census method is that process of the statistical list where all members of a population are analysed. The population relates to the set of all observations under concern. For instance, if you want to carry out a study to find out student’s feedback about the amenities of your school, then all the students of your school would form a component of the ‘population’ for your study.

Sampling Method

A sampling method is a process for choosing sample members from a population. Three (3) common sampling methods are:

Simple random sampling
Stratified sampling
Cluster sampling

Census method and its advantages

Q.1. Explain the census method of collection of data. Give its advantages and disadvantages.
Answer
(A) Census method	● A statistical investigation in which the data are collected for each and every element/unit of the population is termed as census method. ● It is also known as ‘complete enumeration’ or ‘100% enumeration’ or ‘complete survey’. ● It is useful when case intensive study is required or the area is limited. ● Examples: 1. Demographic data on birth and death rates, literacy, workforce, life expectancy, size and composition of a population 2. The census of India is conducted every 10 years.
(B) The following are the advantages of the census method.
(1) Intensive study	● It provides intensive and in-depth information covering many facets of the problems. ● Example: In a population census, not only the number of persons is counted, but the information is also collected on various other parameters like the number of males and females, age, education, marital status, occupational level, income health conditions, etc.
(2) Results are more accurate and reliable	● Since, in this type of investigation, every item of the universe is taken into account, the conclusions are more accurate and reliable.
(B) The following are the disadvantages of the census method.
(1) Costly method	● Since the data are obtained for or from each and every unit of the population, it is a very expensive method of investigation, especially in case of a large population size.
(2) Needs more time and manpower	● Since a large volume of data is to be collected, more time and manpower is required for its collection, analysis, and interpretation.
(3) Not suitable for the large population	● This method is meaningless in the case of an infinite universe where the number of items is unlimited.

Sampling method and its advantages

Q.2. Explain the sampling method of collection of data. Briefly discuss its advantages and disadvantages.
Answer
(A) Sampling method	● The sampling method is the one in which only some of the representative items of the population are selected and the data are collected from these. ● Instead of collecting information for and from all the units of population, we select a sample, i.e., only a few items of the population. ● Conclusions derived from the small sample are generalised for the whole population.
(B) The following are the advantages of the sampling method.
(1) Economical, i.e., low cost	● It is more economical than the census method, as the task of collection and analysis of data is limited only to a small sample, i.e., a few units of the population.
(2) Quick results	● In this method, only a few units are analysed, hence we get quicker results.
(3) Indispensable or greater scope	● The sampling method becomes indispensable, whereas the census method is impracticable. Example: ● If the life of bulbs is to be tested by the manufacturer ● If the quality of nuts and bolts is to be tested ● If blood test is to be carried out ● If the quality of prints is to be tested while printing books
(4) Scientific approach	● The sampling method is more scientific than the census Method, as it is possible to determine the extent of reliability of its results.
(5) Follow up	● Due to the small size of the sample, it is possible to cross-check the data to test the reliability.
(6) Helpful in checking census results	● Due to scientific nature, the sampling method can be used to cross-check the results of the census method.
(C) The following are the disadvantages of the sampling method.
(1) Difficult to achieve cent percent accuracy	● The conclusions of the sampling method are based only on the results of a few items taken from the whole population. Thus, these may not be cent percent correct.
(2) Bias in the selection of sample	● If the investigator is biased, then he might select a sample deliberately. ● In such cases, the selected sample may not be the best representative of the population.
(3) Difficult to select a sample having all the characteristics of the population	● In practice, it is very difficult to obtain a sample that truly represents the population. ● A sample may not have all the characteristics of the population.
(4) Need for specialised knowledge and training	● It is a special technique and beyond the capacity of every person. ● Its use requires specialised knowledge and training.

Difference between Census and Sampling Method

Q.3. Distinguish between census method and sampling method.
Answer:
Parameters	Census Method	Sampling Method
(1) Nature of enquiry	The extensive enquiry is conducted at each and every unit of the population.	The limited enquiry is conducted as only a few units of the population are studied.
(2) Economy	More Time, Money, and Labour It requires a large amount of money, time, and labour.	Less Time, Money, and Labour Relatively less money, time, and labour are required.
(3) Suitability	It is more suitable if the population is heterogeneous in nature.	It is more suitable if the population is homogeneous in nature.
(4) Reliability and Accuracy	The results are quite reliable and accurate under the census method.	The results of the sampling method are less reliable because a high degree of accuracy is not achieved.
(5) Organisation and Supervision	It is very difficult to organise and supervise the census method.	The sampling method is comparatively easy to organise and supervise.
(6) Verification	Under this method, the results of the investigation cannot be verified.	Under this method, the results can be tested by taking out another small sample.
(7) Nature of method	The census method is an old method of investigation and not a very scientific method.	The sampling method is a new and practicable method. It is a scientific method.

The above-mentioned concept is for CBSE Class 11 Statistics for Census Method and Sample Method. For solutions and study materials for Class 11 Statistics, visit our website or download the app for more information and the best learning experience.