Census House: The term 'house' in India covers the greatest diversity of dwellings. In 1872 a house was defined as "any permanent structure which on land, serves or would serve for the accommodation of human beings, or of animals, or goods of any description provided always that it could not be struck and removed bodily like a tent or a mud hut". An attempt was also made to classify the houses as of the 'better sort' and of 'inferior sort'. In the census of 1881 house was defined as the dwelling place of one or more families with thier servants, having a separate principal entrance from the public way. The same definition with slight modification continued till 1951. In 1961 census 'House' was defined as a structure or part of a structure inhabited or vacant, or a dwelling, a shop, a shop-cum-dwelling or a place of business, workshop, school etc. With a separate main entrance. In 1971 census, 'House' was defined 'as a building or part of a building having a separate main entrance from the road or common courtyard or stair case etc. Used or recognised as a separate unit. It may be inhabited or vacant. It may be used for a residential or non-residential purpose or both'.

Family or Household: The household or family was first defined in 1872 as comprising of those who lived together and ordinarily cooked at the same hearth including their servants and visitors. In 1881 Census it was defined as comprising of all those persons who actually slept in the house or compound on the night of 17th February, 1881. From 1891 till 1941 the term 'family' was used in place of Household. From 1951 Census onward again the concept of household was used in Indian Censuses. In 1971 Census a household was defined as 'a group of persons who commonly live together and would take their meals from a common kitchen unless the exigencies of work prevented any of them from doing so'.

The concept of age changed from census to census. In 1872, age 'next birthday' was recorded. From 1881 to 1921 and also in 1951, age completed on the 'last birthday'' was recorded. In 1931 age 'nearest birthday' was recorded. In 1941 Census, the age was recorded 'in years and month'. In 1961 Census, 'age last birthday' was recorded. In 1971 Census the age of the person in total years completed last birthday was recorded.
The direct question on age at last birthday is more economical to process but may yield less precise results, since it more easily permits approximate replies. With all the shortcomings of the question on age, Indian Census has been attempting to it, and the question is bound to continue to be asked in future censuses.

Information on 'Marital Status' was collected for the first time in 1881 Census. From 1881 to 1931 censuses, the population was classified into married, unmarried, widowed or widower. No information was collected regarding 'divorce'. Divorced persons were entered as widowers from 1901 to 1931. It was only in 1941 census that the divorced persons were recorded separately. In 1951 Census, the marital status of the persons was recorded as unmarried, married, widowed and divorced.
No change in the definition of marital status was made in 1961 census except that the term 'unmarried' was replaced by 'never married'. 'Separated' was added with 'Divorced'. The marital status of the prostitutes was recorded as declared by them. In 1971 Census the marital status of a person was recorded under the following heads:-

(1) Never married
(2) Married
(3) Widowed
(4) Separated or Divorced.

From 1881 to 1971 the question on the Place of Birth was recorded with a view to study the migration of the population. The name of the district where the person was born was recorded. In case the person was not born in the State of Enumeration, the Province of birth was also recorded. In 1961 two questions on migration in addition to the Place of Birth were also put to the individuals namely:-

 (i)    Whether born in Village or Town; and
(ii)    Duration of Residence if born elsewhere.

In all censuses from 1881 to 1971, if a person was born outside the Indian Union, the name of the country was also recorded. The duration of residence of a person in the place of enumeration had been asked in the 1961 census to improve the migration statistics as compared to the previous censuses. But still, there are certain implications of using such data for making a detailed inquiry on migration. From these questions on migration, no information can be had regarding the multiple migration of the individuals. The migration statistics collected in the 1961 census are correct if the individual has moved straight from his place of birth to the place of enumeration. But in actual practice the migration may be more than once. Also, even if a person had been born at the place of enumeration, he might have been migrating from place to place and finally settled at the place of enumeration, his omission as migrant is not justified. For making any thorough investigation regarding the migration of population, it is essential to probe into the reasons of migration.

In 1971 census 'Birth place' was again recorded in respect of each person. If the person was born outside the village or town of enumeration it was ascertained whether the place was rural or urban. If the place of birth was outside the district, the name of the district; if born outside the State the name of the State/Union Territory and if born outside the Indian Union the name of the Country was also recorded. In 1971 the migrational particulars with reference to the place of last residence were also collected which yielded valuable and realistic data on internal migration. The information was recorded under the following heads:

Village or Town is recognised as the basic area of habitation. In all censuses throughout the world this dishotomy of Rural and Urban areas is recognised and the data are generally presented for the rural and urban areas separately. In the rural areas the smallest area of habitation, viz., the village generally follows the limits of a revenue village that is recognised by the normal district administration. The revenue village need not necessarily be a single agglomeration of the habitations. But the revenue village has a definite surveyed boundary and each village is a separate administrative unit with separate village accounts. It may have one or more hamlets. The entire revenue village is one unit. There may be unsurveyed villages within forests etc., where the locally recognised boundaries of each habitation area is followed within the larger unit of say the forest range officers jurisdiction.

It is in defining the Urbans areas that problems generally arise. However for the 1971 Census the definition adopted for an urban area which follows the pattern of 1961 was as follows:-

The Director of Census of each State/Union Territory was, however, given some discretion in respect of some marginal cases, in consultation with the State Govt., to include some places that had other distinct urban characteristics and to exclude undeserving cases.

A new concept that had been developed for the 1971 Census for the tabulation of certain urban data was the Standard Urban Area. The essential of a Standard Urban Area are :

 (i)   it should have a core town of a minimum population size of 50,000,
(ii)   the contiguous areas made up of other urban as well as  rural administrative units should have close   utual socio- economic links with the core town and
(iii)  the probabilities are that this entire area will get fully  urbanised in a period of two to three decades.

The question on Caste, Tribe or Race was asked from each individual right from 1872, though the type of information collected was different in different censuses. In 1881, caste if Hindi; sect; if of othe religion, were recorded. In 1891 Main Caste and Sub-division of caste or race was recorded. In 1901 and 1911 censuses, the caste of Hindus and Jains; tribe or race of those of other religions were recorded. In 1921, 1931 and 1941 censuses, caste, tribe or race of all the individuals enumerated was recorded. In the 1931 Census, tabulation of figures for individual castes was limited to :

  (i) Exterior castes;
 (ii) Primitive castes; and
(iii) All other castes with the exception of:
          (a)  those whose members fell short of four per thousand of the total population; and
          (b)  those for which separate figures were deemed to be unnecessary by the local Government.

Pursuant of the policy of the Govt. Of India to discourage community distinction based on Caste, the 1951 Census marked a complete departure from the traditional recording of Race, Tribe or Caste and the only relevant question on caste or tribe incorporated in the Census Schedule was to enquire if the person enumerated was a member of any 'Scheduled Caste', or any 'Scheduled Tribe' or any other 'Backward class' or if he was an 'Anglo Indian'.

In 1961 and 1971 Censuses the information was collected only for each Scheduled Caste and Scheduled Tribe.

The information on economic activity of the individual was collected right from the 1872 census. In the censuses of 1872 and 1881 only one question relating to 'occupation' was asked from the individuals and the persons were classified according to the various occupations. In 1891 the concept of 'means of subsistence' was introduced. The question on means of subsistence was recorded in case of every individual. In case of dependents the occupation of the person on whom they were dependent was recorded. From 1901 to 1921 the information on principal and subsidiary occupation or means of subsistence of actual workers was recorded. In case of dependents, the occupation of the persons on whom they were dependent was also recorded. In all these censuses the term 'actual worker' also included persons who were in receipt of income without doing work such as rentiers and pensioners etc. In 1931 Census, the term 'actual worker' was replaced by the 'earner'. The population was classified as earners, working dependents and non working dependents. The Principal and subsidiary occupation of each worker was recorded. Occupation of dependents was recorded under the caption 'subsidiary occupation'. Besides, the Industry in which a person was employed was also noted. In 1941 Census 'Means of Livelihood, in order of importance' was recorded in respect of each worker. It was also enquired whether a particular means of livelihood existed throughout the year, if not, for what part of the year. If a person was employed by someone else, the information about his business was also noted. In case of 'dependent' it was enquired whether he was wholly or partly dependent on anyone else. If so, means of livelihood of person on whom dependent was recorded. The information relating to the employment of (a) paid assistants, (b) members of household was also collected. The question on 'Are you in employment now? Was also asked in regard to means of livelihood of a person shown as partly dependent. Owing to war the tabulation of 1941 Census was greatly curtailed. But Shri Yeatts, the Census Commissioner for India, shrewdly decided to retain a 2 per cent random sample of the original individual census slips of each state. On the recommendations of the Population Data Committee the Government of India decided to entrust the Y-Sample slips in 1945, to the Indian Statistical Institute, Calcutta where the information in the slips was transferred to Hollerith cards. From these cards Means of Livelihood and Industries Tables were prepared for the states for which no such tables had been prepared at the time of the 1941 Census. The 'Means of Livelihood' tables were prepared for the whole State and also for its constituent districts. In the State table, the number of independent or self-supporting persons having their principal means of livelihood in different occupational groups (classified according to the class of subsidiary means of livelihood, if any) were shown. The number of partly dependents following any specified occupation as their 'Supporting Means of Livelihood' was also given. In the district tables, however, such information was given only by broader occupational groups. The table on Industrial classification of persons was prepared only for the State as a whole. This showed the number of workers (employees)engaged in the different Industries (groups) classified according to the class of worker.

The 1951 Census ascertained the two economic characterisitcs of every individual-his economic status and his means of livelihood. The following three questions were prescribed:-

  (i) Economic Status
          Part One: Dependency
          Part two: Employment
 (ii) Principal Means of Livelihood
(iii) Secondary Means of Livelihood.

According to economic status every person was classified as "a self supporting person" or "an earning dependent" or "a non-earning dependent". The terms were defined as follows:

It was found that the concept of dependency adopted in 1951 census had a tendency to suppress the important sector of workers as a consequence of which the number of economically active persons engaged in agriculture and traditional cottage industries and services where women were mainly employed showed very little increase compared to the increase in general population. It was felt that by the introduction of income, persons who worked in family enterprises without wages in cash or kind but who shared the profits were likely to be omitted. This was so especially in the case of families who partake in household cultivation. It was, therefore, decided that the economic data in 1961 should be collected on the basis of work i.e. the population should be divided into two classes, 'Workers' and 'Non-workers'. The basis of work adopted in 1961 census was as follows:

In the case of seasonal work like cultivation, livestock, dairying, household industries, etc., if a person had some regular work of more than one hour a day throughout the greater part of the working season, he was to be regarded as a worker. In the case of regular employment in any trade, profession, service, business or commerce the basis for work would be satisfied if the person was employed during any of the fifteen days preceding the day on which he was enumerated. A person who was working but was absent from his work during the fifteen days preceding the day of enumeration due to illness or other cause was a worker. A person who was offered work but had not actually joined was treated as a non-worker. A person under training as apprentice with or without stipend or wages was regarded as a worker. An adult woman engaged in household duties but not doing any productive work, to augment the family resources was considered as non-worker. Persons like beggars, pensioners, etc., who received income without doing any work were regarded as non-workers. A public or social service worker who was actively engaged in public service activitity or a political worker who was actively engaged in furthering the political activity of his part was regard as a 'worker'. The worker was further classified into one or more of following groups:

1.  Working as Cultivator,
2.  Working as Agricultural labourer,
3.  Working at Household Industry,
4.  Doing work other than (1), (2) and (3).

In 1971 Census considerable departure was made in respect of the economic questions. The main activity of a person was ascertained according as he spent his time basically as a worker producing goods and services or as a non-worker. For regular work in Industry, Trade or Services the reference period was the week prior to the enumeration and for seasonal work such as agriculture the last one year. Work involved not only the actual work but also effective supervision and direction of work. The person was categorised according to the main activity returned by an individual. The classifications adopted were as follows:

  (i)   Working as Cultivator;
 (ii)   Working as Agricultural Labourer;
(iii)   Working at Household Industry' and
(iv)   Other Workers.