Column | Studying Demographic Changes Without Demographic Data 

By all accounts, the High-Level Committee on Demographic Changes (or the Demographic Panel), set up on May 26, 2026, faces the task of examining a complex set of population developments for which empirical evidence is limited, while the subject itself has considerable political significance. The long delay in conducting the population Census, the country's basic source of demographic data, compounds the difficulty.

The Committee has been constituted before the results of the forthcoming Census are available, even though many demographic questions can be meaningfully examined only with Census data available for small administrative areas. Moreover, while the Census Commissioner is a member of the Committee, the Committee does not itself constitute a standing demographic research institution with an established system of data collection and analysis. It will therefore have to depend substantially on data supplied by government departments and, where necessary, on outside expertise.

At the same time, the forthcoming Census is itself being conducted on a considerably expanded scale, raising questions about the purpose, availability, confidentiality and eventual use of the additional information being collected. The limited purpose of this note is to examine the empirical difficulties the Committee faces if it is to address the assigned terms of reference scientifically. 

According to the Government's announcement, demographic change is a serious issue linked not only to sovereignty but also to national security, law and order, changes in social structure and the protection of tribal societies. The Committee is expected to undertake a comprehensive assessment of demographic changes occurring across India due to illegal immigration and other abnormal causes and to analyse such changes at the level of religious and social communities. It has been given one year to submit its report, extendable by up to six months. 

The terms of reference make the intended scope clearer. The Committee is to examine possible causes of demographic change, including cross-border activities, illegal immigration, abnormal settlement patterns and orchestrated migration. It is also required to analyse structural population changes among religious and social communities, particularly where these appear to deviate from broader demographic trends. More significantly, it is expected to recommend an operational mechanism for the legal, fair and time-bound identification, detention and deportation of illegal immigrants, strengthen border management and monitoring systems, and improve coordination between the Centre and the States. 

The Committee, thus, is not merely being asked to study demographic change in the conventional sense, a task that could be undertaken by demographers using population, fertility, mortality and migration data. It has also been asked to investigate illegal immigration and its possible demographic consequences and to propose mechanisms for dealing with it. The Home Minister's statement at the time of the Committee's constitution explicitly linked the exercise to "infiltration" and to mechanisms for addressing the resulting demographic changes. This creates an important methodological problem: the existence and magnitude of illegal immigration cannot simply be inferred from changes in the size or religious composition of a population. 

The basic difficulty is that neither the population Census nor the regular sample surveys are designed to establish the legal status of an individual's presence in the country. Census data can record place of birth and previous place of residence and can therefore provide information on migration, but these variables do not establish whether a migrant is legally or illegally present. Nor would one necessarily expect a person whose legal status is uncertain to provide information that would establish that status. An unusual increase in the population of a particular area or community can therefore be a starting point for investigation, but it cannot by itself demonstrate illegal immigration. 

A more rigorous approach would be to compare observed population changes with those expected from the normal demographic processes. Population projections for a State or district can, in principle, be constructed from fertility, mortality and migration parameters. But such an exercise becomes increasingly difficult at smaller geographical levels because of the non-availability of reliable estimates of these parameters. The data currently available provide only a limited scope for making the kind of fine-grained attribution that the Committee's mandate requires. 

The difficulty becomes even more apparent from reports that the Committee has recently circulated a 35-point questionnaire to State and Union Territory governments seeking administrative data for the past 15 years. The reported requests include religion-wise information on birth registrations, school enrolments, ration cards, vehicle registrations and property transactions; unusual increases in Aadhaar, voter-ID and ration-card registrations; forged identity documents; information arising from the Special Intensive Revision of electoral rolls; GIS mapping of religious educational institutions; information relating to tribal land transfers and encroachments; intelligence assessments concerning religious conversion among Scheduled Tribes; detention centres; cases allegedly linking undocumented migrants with organised crime or narcotics; and mechanisms for monitoring unauthorised settlements. Reports also indicate that States have found it difficult to provide much of the information in the form requested because their administrative systems do not ordinarily record religion for these transactions. 

This raises a basic question: are these data actually collected and maintained in a form that permits the proposed analysis? 

India's administrative statistical system was not generally designed to record religion across all government transactions. There are, of course, important exceptions. The Census collects religion, and the 2011 Census provides religion-wise population data at several geographical levels.

The education system also contains some religion-related information. UDISE+, for example, has collected information concerning minority communities, while the higher-education system reports enrolment of Muslim students and students belonging to other notified religious minorities. Such information, however, is collected for particular administrative or statistical purposes and does not automatically provide a consistent religion-wise series for every district and every administrative transaction over 15 years. 

Similarly, religion has been included in the statistical portion of prescribed birth and death registration forms in various State rules. But the existence of a field in a registration form does not mean that the information is routinely published, integrated with other administrative datasets, or available in a common national database, permitting the precise cross-tabulations now being sought. 

The problem is even greater for such transactions as property registration, vehicle registration and many identity-related records, where religion is generally not a standard variable. Aadhaar, for example, is not a database of religious identity. Thus, even where information may exist somewhere in the administrative system, it does not follow that it can readily be retrieved by religion, district, year and other characteristics. Producing such tables retrospectively would require either linking disparate administrative databases or generating variables that were never originally recorded. 

This is particularly consequential for the Committee's proposed analysis of "abnormal" demographic change. If religion is not recorded in the underlying administrative transaction, an attempt to reconstruct religion from the names or other indirect identifiers would produce a fundamentally different kind of data. Such classification would not be equivalent to self-reported religion and is likely to generate systematic biases. The problem would become still more serious if the objective were to identify relatively small geographical areas or border settlements. 

The Committee therefore faces a difficult choice. It can rely on the limited demographic information generated by the Census and other established statistical systems, which cannot directly identify illegal immigrants; or it can rely heavily on administrative responses to its questionnaire, many of which may not be based on systematically recorded variables. Neither route by itself provides a sound empirical basis for establishing the magnitude, geographical distribution or community-wise composition of illegal immigration. 

The larger issue, therefore, is not whether demographic changes exist or whether illegal immigration is a legitimate subject for investigation. It is whether the available data can establish the nature, magnitude and causes of those changes with the degree of precision implied by the Committee's mandate. A demographic investigation cannot become scientifically stronger merely by requesting more administrative data. The data must have been systematically collected, consistently defined, geographically comparable and capable of being independently verified. Otherwise, there is a real risk that administrative compilations, rather than statistically designed evidence, will become the principal basis for concluding demographic change. 

(Views expressed by the author are personal)