Demography, Sources of Population Data and Census

Demography is the science of population. It is the statistical study of population. The word 'Demography' is derived from the two Greek words 'Demos' and 'Graphy'. The word Demos means people and Graphy mean to write or to study. The word 'Demography' was first used by Achille Guillard in 1855 AD in his book "Elements of human statistics or comparative demography". He is known as the father of Demography. There are various definitions of demography given by various scholars.
The multilingual demographic dictionary has defined demography as: "Demography is the scientific study of human population, primarily with respect to its size, structure, distribution and its growth rate". Demography can be defined in two dimensions which are discussed below,

Formal Demography

It is known as mathematical demography. It is the quantitative study or mathematical study of human population. The UN multi-lingual demographic dictionary has defined formal demography as "Formal demography is the scientific study of human population primarily with respect to their size, structure and development". Similarly, according to Lucus (1987)- "Demography is a science dealing with marriage, birth, death, and migration of human population.It also involves the size, geographical distribution and composition of the population and how these changes over time".

Social Demography

Social Demography explains the issues of population studies by relating with the social and economic aspects. Social demography also studies about various subjects like Biology, Psychology, Medicine, and Geography, Environment Science and the contents of formal demography as well. So, it is also known as a multidisciplinary subject.
According to Shryock and Siegel (1976), "Social demography or population study is concerned not only with population variables eg: fertility, mortality, and migration but also with the relationship between population changes and other variables like social, economic, political, biological, genetic, geographical and the like".
Social demography deals with the relationship between population changes and other aspects like social, economic, political and geographical aspects. It is also known as population study.

Sources of Population Data

We record the population of particular area living at a particular time by using various methods and sources. The sources are divided into two types, primary sources, and secondary sources. Primary sources are like the census, vital registration system whereas secondary sources are like textbooks, research reports,population monographs etc. Population data provide us information about the socioeconomic and demographic characteristics of the human population. Population data is also known as demographic data. It provides information about birth, death, migration, age, sex, marital status, nationality, religion, literacy, language, occupation, and family planning of a particular place for a particular time period. This information is important for government. This information helps the government to make plan and policies and carried out developmental activities. It also helps various non- governmental organizations to prepare plan and policies and conduct various activities.

Primary Sources

In primary sources, the data are collected directly from the field observation or households by using various data collection tools like questionnaire, observation, interview, etc. They are usually conducted by government and some non- governmental organization. Primary sources of population data are the first hand data.

The primary sources of population data are discussed below:

• Census
• Vital registration system
• Administrative records
• Sample surveys
• Population register

Census

Census simply means the counting of people of a certain area at a certain time. It is the main source of demographic data. It is conducted by the government to know the overall population of the country. In the census, the population of the certain area is recorded based on age, sex, caste, religion etc. It is usually carried out in every 10 to 5 years. The UN (1970) has defined census as, "A population census is a total process of collecting, compiling, evaluating, analyzing and publishing demographic, economic and social data pertaining at a specified time to all persons in the country or in a well delimited territory of the country".

Methods of census

Census can be conducted by using three methods which are discussed below:

• De facto method: In this method, the census is conducted on the basis of usual place of residence. During this method, the government declares the actual date as 'census date' and the people are pre-informed of counting. People are counted where they are found. This method is also known as 'one night enumeration' as it is conducted in the night. This method is used mostly in urban areas where highly educated people live.
• De jure method: In this method: the census is conducted on the basis of the permanent address of people. The people or foreigner living in a temporary residence are not calculated. The government declares the census period (2 to 3 weeks). The population counting should be completed within the given period. This method is also known as period enumeration. This method is used in many developing countries.
• Modified De- jure method: This is the modified form method of De Jure method. It is an alternative and more practicable approach over the De jure and De facto census technique. Here, the people are counted on the basis of their usual place of residence (the residence where the respondents are living for more than six months is perceived as a usual place of residence). This method is used in most of the countries. The method of census used in Nepal is modified De- jure method. Nepal is using this method since 1952/54 AD. In this method students in hostels, Armed forces in barracks as well as beggars, sages, and hermits are also enumerated.

Historical Development of Census

Talking about the historical development of census, the first census was conducted in Bolivia in 4000 BC, China in 3000 BC, Egypt in 2500 BC and India in 330 to 270 BC. But these censuses were not systematic and scientific. The modern and orderly census was first started in New France and Acadia in 1665 AD. The census was then conducted regularly and orderly in USA (1790), England 91801), India (1872) etc.

In Nepal, the first census was conducted in 1911 AD. This census was not systematic and scientific. The modern type of scientific census was started in 1952/54 but it was of not international standard as it was not conducted properly. It was conducted at two different times. It was conducted in eastern Nepal in 1952 and western Nepal in 1954. The census of 1961 AD was conducted properly and was the first census of international standard. Since then, the census has been conducted in every 10 years with various improvements. The latest census of Nepal is 11th Census which was held in 2011 AD. Today, the census are conducted under the UN guideline. So, the schedule of the census is found almost similar globally.

Features of Census

• It provides first-hand information.
• It is the data bank of a human population.
• It is conducted by using two methods, Defacto, and Dejure method.
• Every unit of population is counted without duplication or omission.
• It is conducted at a definite time period and regular interval.
• It covers all the parts of the country.

Information to be collected in the Census

The Census is conducted by most of the countries of the world under the guideline of UN. It has a list of recommended and other useful topics to be covered by a census from 1970 AD onwards. This gives all the information of the individual. It is useful universally. The UN recommended census consists of following characteristics,

Geographical Characteristics

Following information are collected on this topic.

• Birthplace
• Place of usual residence
• Place where staying at the time of census
• Place of the previous residence
• Duration of residence
• Place of work

Personal and Household Characteristics

Following information are collected under this heading.

• Age
• Sex
• Caste/ethnic group
• Marital status
• Relation to the head of the household
• Religion
• Language
• Literacy
• Number of live births
• Age at first marriage
• Number of children alive
• Language
• Nationality

Economic Characteristics

Following information are collected on this topic.

• Occupation
• Employment status
• Source of livelihood
• Socioeconomic status
• Sources of income