Demographic Data Collection; Differences Between Census and Sampling

Demographic Data Collection; Differences Between Census and Sampling

Meaning of Demographic Data Collection 

Demographic data are data output of demography which is the study dealing with the human population. Demographic data can be related to the Earth, the same as geographic data. Demographic Data usually represent geographical location, identification, or describe populations.
This field of science and research can be applied to anything about the dynamic nature of the human population including how it changes over time and what factors are affecting the changes. This study also covers aspects of human population such as the size, structure, distribution, spatial and temporal changes in response to birth, death, aging or migration.
Demographic data which are most commonly used include crude birth rate, general fertility rate, age-specific fertility rates, crude death rate, infant mortality rate, life expectancy, total fertility rate, gross reproduction rate and net reproduction ratio.
Demographic data can be used in analyzing certain patterns and trends related to human religion, nationality, education and ethnicity. These data are also the basis for certain branches of studies like sociology and economics.




Collection of demographic data can be broadly categorized into two methods: direct and indirect. Direct demographic data collection is the process of collecting data straight from statistics registries which are responsible for tracking all birth and death records and also records pertaining to marital status and migration.
Perhaps the most common and popular methods of direct collection of demographic data is the census. The census is commonly performed by a government agency and the methodology used is the individual or household enumeration.
The interval between two census surveys may vary depending on the government conducting. In some countries, a census survey is conducted once a year or once every two years and still others do census once every 10 years. Once all the data collected are in place, information can already have derived from individuals and households.
The indirect method of demographic data collection may involve only certain people or informants in trying to get data for the entire population. For instance, one of the indirect demographic data methods is the sister method. In this method, a researcher only asks all the women on the number of their sisters who have died or have had children who have died at what age they died.
From the collected data, the researchers will draw their analysis and conclusions based on indirect estimates on birth and death rates and then apply some mathematical formula so they can estimate trends representing the while population. Other indirect methods of demographic data collection may be to collect existing data from various organizations who have done a research survey and collate these data sources in order to determine trends and patterns.



A.    Definition of Census
A well-organised procedure of gathering, recording and analysing information regarding the members of the population is called a census. It is an official and complete count of the universe, wherein each and every unit of the universe is included in the collection of data. Here universe implies any region (city or country), a group of people, through which the data can be acquired.
Under this technique, the enumeration is conducted about the population by considering the entire population. Hence this method requires huge finance, time and labour for gathering information. This method is useful, to find out the ratio of male to female, the ratio of literate to illiterate people, the ratio of people living in urban areas to the people in rural areas.
Census is the official count of population of a country. The United Nations defined census as the total process of collecting, compiling and publishing demographic, economic and social data pertaining, at a specified time or times, to all persons in a country or delimited territory.

According to the UN, the census is featured by the following aspects:
(i)                 Individual enumeration,
(ii)              Universality within a defined territory,
(iii)            Simultaneity and
(iv)             Defined periodicity.

Among the recommended and useful topics to be covered in a census are the following:
Firstly, Geographic Characteristics: place where found at time of census or place of usual residence, place of birth, duration of residence, place of previous residence, place of work;
Secondly, Personal and Household Characteristics: sex, age, relationship to head of household/ relationship to head of family, marital status, duration of marriage, marriage order, children born alive, children living, citizenship, literacy, school attendance, educational attainment/educational qualification, national/ethnic group, language, religion;
Thirdly, Economic Characteristics: type of activity, occupation, industry, status, main sources of livelihood.

Some of the useful derived topics are:
(i)                 Geographic Characteristics: total population, locality, urban and rural,
(ii)              Personal and Household Characteristics: household composition, family composition,
(iii)            Economic Characteristics: socio-economic status, dependency, etc. Based on de jure or de facto procedures all people are counted as resident or present in a defined territory along with other topics as mentioned above.




B.     Definition of Sampling
We define sampling as the process in which the fraction of the population, so selected to represent the characteristics of the larger group. This method is used for statistical testing, where it is not possible to consider all members or observations, as the population size is very large.
As statistical inferences are based on the sampling observations, the selection of the appropriate representative sample is of utmost importance. So, the sample selected should indicate the entire universe and not exhibit a particular section. On the basis of the data collected from the representative samples, the conclusion is drawn from the whole population. For instance: A company places an order for raw material by simply checking out the sample.
The units which constitute sample is considered as ‘Sampling Units’. The full-fledged list containing all sampling units is called ‘Sampling Frame





Key Differences Between Census and Sampling
The paramount differences between census and sampling are discussed in detail in the given below points:
  1. The census is a systematic method that collects and records the data about the members of the population. The sampling is defined as the subset of the population selected to represent the entire group, in all its characteristics.
  2. The census is alternately known as a complete enumeration survey method. In contrast, sampling is also known as a partial enumeration survey method.
  3. In the census, each and every unit of population is researched. On the contrary, only a handful of items is selected from the population for research.
  4. Census, is a very time-consuming method of survey, whereas, in the case of sampling, the survey does not take much time.
  5. The census method requires high capital investment as it involves the research and collection of all the values of the population. Unlike sampling which is a comparatively economical method.
  6. The results drawn by conducting a census is accurate and reliable while there are chances of errors in the results drawn from the sample.
  7. The size of the sample determines the probability of errors in the outcome, i.e. the larger the size of population the less are the chances of errors and the smaller the size; the higher are the chances of errors. This is not possible with census as all the items are taken into consideration.
  8. Census is best suited for the population of heterogeneous nature. As opposed to sampling which is appropriate for homogeneous nature.

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