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Data discrepancies

By Debolina Kundu

We cannot address the problems of urban poverty and slum conditions until we know their magnitude and details. Masses of data are available, but given the inadequacy of official definitions of slums, it is limited in scope, coverage and standardisation/comparability

Non-availability of adequate and reliable data has often been voiced as a major concern among researchers working on diverse aspects of urban development in India. It is well-known that the main problem in this context is not that the data does not exist or is not collected at sufficient levels of disaggregation, but that much of the information has problems of coverage and definitional anomalies and is not rendered comparable and made accessible to potential users. Information of a quantitative nature is available from national data-gathering agencies like the Population Census and National Sample Survey Organisation (NSSO) which bring out datasets at regular intervals. Enormous amounts of information are also generated by government departments, public and semi-public agencies engaged in urban development activities, in the course of their funds disbursal, programme implementation and other routine administrative work. It is rather unfortunate that all these datasets are only put to limited use in working out a development strategy at district, state or national levels; the data is used only for decision-making within the department or undertaking the collection of information. Consequently, it does not become an input in policymaking, planning and academic research at a higher level, remaining in data graveyards unless requisitioned by a state or national agency for a specific purpose, after meeting a complicated procedure. Since the basic concepts used for data-collection are not standardised and no rigorous format is designed for their compilation, it takes effort and resources to make them temporally and cross-sectionally comparable and useful for research or policymaking. Even the data provided by the national data-gathering agencies, like the census and NSSO, have serious problems in scope and coverage.

Interestingly, urbanisation, housing/slums and access to amenities reflecting deprivation and poverty at the household level are areas where massive amounts of information are available with the national and state data-generating agencies. It is a clear case of over-collection of data on the one hand, and low use and usability of the collected data on the other. The main reason for this is that the agencies do not provide the data in a comparable format and there is no organisation which can compile and clean up the data from all possible sources, removing the anomalies due to definitional changes and coverage, as part of an urban information system.

In the present context of urbanisation in the country, it is important to collect comparable and robust statistics on urban population, poverty and other socio-economic deprivations including slum conditions in different states and size classes of urban centres, and make them available to planners, administrators and researchers. The growth of urban populations at a rate significantly higher than that of the general population, and low investment in infrastructure and civic services have created problems of low employment growth in formal sectors and deficits in basic amenities in urban centres. This has resulted in a consolidation of informal employment and poverty, on the one hand, and poor quality of life and growth in slum populations, on the other. Although the two concepts -- poverty and slums -- have overlapping elements, both in conceptual and operational usages, there are significant differences in terms of causes, characteristics and methods of alleviating them which makes the issue of data compilation with total clarity in definitions extremely important. The issue assumes even greater significance in the Twelfth Plan in the context of the government’s commitment to alleviate urban poverty and make India slum-free in a time-bound manner.

Given this scenario, the second section of this paper takes stock of the existing data on slum conditions, to identify data gaps and propose measures to clean these up for use. The key objective is to review the concepts of slums as used in official literature and policy documents, and critically analyse the available database, highlighting the deficiencies that prevent effective policy formulation and implementation. The final section puts forward a perspective for making the datasets comparable and usable in policymaking and makes a few recommendations for that purpose.

Data on slums

To design a macro-level strategy for alleviating poverty and making cities slum-free, the first requirement would be an assessment of the magnitude of the problem. Data on slums has been collected at the city level by municipal bodies, other local agencies and individual researchers for the past several decades. Unfortunately, these are extremely haphazard and fragmentary and it is difficult to make any cross-sectional comparison or draw temporal inferences based on them. As the information is gathered by different agencies for different purposes, there is no standard format for data-collection and tabulation and consequently, no robust database on slums could be built at the national level. Given the diversity and variation in quality of field-based data, no research study has been able to tie or put together secondary and primary data for the purpose of cross-validation or drawing inferences going beyond the city level.

India stands committed to meeting the Millennium Development Goals during the period 1990-2015 (1). It is surprising that as far as Target 12, that of ‘achieving significant improvement in the lives of at least 100 million slum-dwellers’, is concerned, India Country Report 2009 simply notes that the “pattern of change (is) not discernible due to lack of sufficient data” (2). There cannot be any more telling reason why collecting reliable information on the number and characteristics of slum populations is an urgent necessity in the country for launching any programme addressing their problem.

Slum data from population census

Data pertaining to slums in the 1981 Population Census was collected through statement IVA of the Town Directory, forming part of the District Census Handbook and not through the canvassing of questionnaires at the household level, as a regular census operation in the field. Information was obtained by the Directorate of Census Operations from the urban local bodies and was restricted to notified and recognised (3) slums, as existing in 1979. Only 12 states that reported slums were covered (4). The only union territory (UT) covered was Delhi, which accepted the incidence of a slum population. Unfortunately, Occasional Paper No 3, which brought out slum-related information in 1988, does not include Delhi because of non-availability of information on civic amenities in its slums.

The percentage of slum populations in the total population of towns reporting slums works out to 15% both for Class I and Class II towns. It is difficult to accept that there is no slum-like situation in towns other than the 269 centres reporting their existence in 1981. In towns below the Class II category, deficiencies in terms of housing conditions, water supply, sanitation, electricity, etc, are much more serious than the higher-order towns. This can be confirmed from the information on these three basic amenities provided in the Town Directory. A comparison of towns reporting the existence of slums with those not reporting them in terms of access of households to basic amenities, the main criteria for identifying slums, reveals that the latter are indeed worse-off in relative terms.

The Occasional Paper notes that “there might be notified slums in smaller towns, but it was difficult to collect data in respect of such slums, particularly the census towns which did not have local authorities such as municipalities to provide the requisite information”. The census is, thus, circumspect in reporting information on slums and not categorical that the towns not reporting these did not actually have any slum. It mentions “information not made available” against a number of cities and towns instead of noting that these actually have no slums. It is possible then to stipulate that slum-dwellers constitute about 15% of total urban population in the 12 states if one assumes that cities and towns that do not report slums are no different from those reporting them, and it is only administrative factors and differences in understanding and interpretation of the concepts that have resulted in the ‘error’ of non-reporting.

The 1991 Census was a small improvement on its predecessor in terms of coverage. The information came from states reporting slums in the previous census, except for Jammu and Kashmir where the census could not be conducted in 1991. The additional units in this census were the state of Kerala and the UTs of Goa, Delhi and Pondicherry. It once again covered only the notified/recognised slums of Class I and Class II cities/towns. The number of urban centres reporting slums in these 15 states and UTs were 247 and 260, as per the Town Directory Statements.

The Registrar General of India (RGI) has for the first time collected detailed demographic data, both for notified and non-notified slums in 26 states and union territories of the country, through its household schedule in 2001 (see Table 1). The following were the three criteria for the identification of slums: (a) areas notified as ‘slums’ by state/UT administrations, housing and slum boards and local governments under any Act including a ‘Slum Act’, (b) areas not notified as slums under any Act but recognised as such by the above-mentioned agencies, and (c) compact areas of at least 300 population or about 60-70 households in poorly-built congested tenements in an unhygienic environment, usually with inadequate infrastructure and lacking in proper sanitary and drinking water facilities. Notably, the 1981 and 1991 Census covered only slums identified by Criteria A and B. The inclusion of non-notified and unrecognised slums therefore took place for the first time in 2001 through application of Criterion C.

Table 1: Changing slum populations, estimated by different agencies

Source Year/Period Slum population
Census of India, Occasional Paper
No 3 of 1988, Foreword
Eighties 20%
Census of India, Occasional Paper
No 3 of 1988 (269 cities/towns)
1980 15.10%*
Sixth Plan 1985 33.1 million
Town and Country Planning
1990 51.2 million
Census of India, 1991
(507 cities/towns)
1990 18.38%*
Town and Country Planning
2001 61.82 million
Census of India, 2001
(640 cities/towns; all 50,000+)
2000 42.56 million; 23.1%*
Census of India, 2001
(785 cities/towns; all 50,000+)
2000 44.61 million; 23.0%*
Census of India, 2001
(958 towns; all 20,000-50,000)
2000 7.74 million; 26.4%*
Pronab Sen Committee 2010 75.3 million; 26.3%
Census of India, 2011
(all 2,543 towns/statutory towns)
2011 13.7 million households;
69th Round of the NSSO 2012 9 million households

Note: Percentage figures with a star are computed by taking the figures of urban centres reporting slum populations

In the first phase, Census 2001 collected information on slums from 640 urban centres that had reported populations of 50,000 or above in the 1991 Census, of which 378 were Class I cities and the others belonged to the Class II category. However, on the recommendation of the Parliamentary Standing Committee on Demands for Grants and the Ministry of Housing and Urban Poverty-Alleviation, it has covered 1,321 additional towns (1,151 with 20,000-50,000 population and 170 with more than 50,000 population) in the second phase. Of these, 1,103 have reported having slums (958 towns with a population of between 20,000 and 49,999 and 145 with more than 50,000).

The 2001 Census is an improvement over the preceding ones in terms of slum data as the information is now collected at the household level with all-India coverage by census officials who also play a role in the identification of slums. Further, non-notified slums are identified across the states, at least theoretically, using standardised criteria relating to settlement size, congestion, unhygienic environment, inadequacy of infrastructure and basic amenities. Inclusion of towns with populations of between 20,000 and 50,000 in the second phase has made it possible to assess the slum situation in these smaller towns as well.

There are significant differences between the information pertaining to slums from Population Census 2001 and the earlier two censuses. The former gives detailed demographic and socio-economic data for slum areas. This information is also provided for each of the slums identified in metropolitan cities. The Census of 2001 reports 42.6 million people living in slums in 640 cities with more than 50,000 people that reported a slum population, covered in the first phase. They constitute 23.11% of the total population residing in these urban centres.

How appropriate would it then be to assume that the states/UTs and cities and towns not reporting slums actually do not have any slums, or that slums occur only in large cities with a population of above 50,000? It is well-known that the objective and process of notification of slums varies widely across states and urban centres. Administrators in a few states consider it a reflection of bad governance to report slums to a national agency. Others have taken this as an opportunity and instrument to secure funds for infrastructural

improvements from higher authorities. In a few states, slum notification takes place when the administration wants to acquire land under slum development projects and launch related activities. The notification or recognition of slums is therefore a matter of policy and programme rather than a reflection of certain physical living conditions. The RGI admits that the “concept of slums and their definition vary considerably across the states depending upon the socio-economic conditions or local perceptions prevailing in the society”. It is therefore extremely difficult to work out a figure for percentage of slum population at the national level, particularly due to non-reporting of data.

For the purpose of the 2011 Census, slums have been categorised and defined as the following three types -- notified slums, recognised slums and identified slums (5). For the first time in this census, datasets on housing stock, amenities and assets based on the Houselisting and Housing Census are being released. In Census 2001, slum information was released only on demographic characteristics based on population enumeration.

For this purpose, slum blocks were identified in statutory towns with a population of 20,000 by the local authorities in the population enumeration phase. In Census 2011, slum blocks have been delineated in all statutory towns irrespective of population size. Out of 4,041 statutory towns in Census 2011, slums have been reported from 2,543 towns. Although small slum clusters are now more prevalent compared to the big sprawls of earlier times, the census authorities persisted in using the old 60-70 household definition. Also, dwellings with roofs or walls of GI sheet were not counted as slums. These factors are responsible for the underestimation.

Slum data from National Sample Survey

The first systematic survey on slum conditions was conducted by the NSSO in its 31st Round in 1977. It, however, had been carrying out surveys on housing conditions and basic amenities since the 7th Round, conducted in 1953-54. These provide information on structural aspects of dwelling units and basic amenities (6). Subsequently, a comprehensive survey on housing conditions was undertaken in the 28th Round (120,000 households), spread over a period of nine months. The 44th Round of the survey was similar in scope and content, covering only 74,000 households, but was spread over one year. These surveys provided extremely useful information on quality and nature of housing and access to basic amenities separately for rural and urban areas. In the two subsequent surveys, the 49th Round and the 58th Round, information on housing and basic amenities was collected along with slum characteristics and certain other related aspects, and provided rich information on structural aspects of dwelling units as well as on construction activities of households in the preceding few years. These enable cross-tabulation of households by housing quality and access of households to basic services in slums, non-slum areas and squatter settlements, although the presentation of data in these rounds varies significantly.

The second nationwide survey on the particulars of slums was conducted by the NSSO in its 49th Round which combined this with the regular survey of housing conditions, as noted above. In the coverage, however, the new census towns got excluded, as happens in all NSSO surveys, because the latter takes the last census frame as the basis for data-collection. Besides the declared slums, “compact settlements with a collection of poorly built tenements, mostly of temporary nature, crowded together usually with inadequate sanitary and drinking water facilities in unhygienic conditions” were identified as slums belonging to the 'undeclared' category. The definition of undeclared slums was thus noted to have remained unchanged as in the 31st Round. One difference, however, was that the minimum number of households in a settlement to make it a slum was brought down from 25 to 20 only. Also, a new concept of squatter settlement was introduced in this round, which was unauthorised settlements with unauthorised structures but not categorised as slums.

The third slum survey was conducted in the 58th Round (2002) wherein only slums in urban areas were covered in the whole country (7). Besides, it assessed the housing conditions, levels of village amenities and consumption expenditure and brought out separate reports pertaining to all four themes. The survey designated areas declared as slums by respective municipalities, corporations, local bodies or development authorities as 'notified slums' and not declared slums. It also included non-notified slums whose definition was the same as of undeclared slums in the earlier NSS rounds. It provided extremely rich and detailed information on households residing in different types of structures and having differential plinth areas, ownership, monthly per capita expenditure, access to and distance from different basic amenities, classified by slums, squatter settlements and other areas. Information on residential construction undertaken in the last five years, their costs, sources of financing, particulars of dwelling units, land owned elsewhere in the country, etc, was also provided.

The 65th Round of the NSSO is spread over the entire year from July 2008 to June 2009, as in the 44th Round. It is, however, different from two preceding slum surveys that were restricted to six-month periods only. It deals with the availability and not adequacy of facilities as in the preceding surveys. The coverage of slum conditions is restricted to urban areas, like its predecessor. The information on housing conditions is collected through Schedule 1.2, as in the 58th Round, although the schedules are significantly different from each other.

The 69th Round of the NSSO reported just under 9 million households as slum households. Roughly one-eighth of India’s urban population lives in slums, as per the NSSO. The number is significantly lower than the 14 million slum households identified by the 2011 Census. An estimated 8.8 million households lived in these slums, about 5.6 million in notified and 3.2 million in non-notified slums. The number of slums came down by 32.3% to 33,150 in urban India, in 2012. The NSSO, like the census, counted both slums notified by the state government and non-notified slums. The NSSO definition of a non-notified slum was slightly more generous than that of the census; any crowded settlement with poor sanitation and at least 20 households was considered a slum by the NSSO, while the census required there to be at least 60-70 households.


An overview of the data situation on poverty-linked deprivation, housing conditions and slums reveals serious problems of temporal and cross-sectional comparability in information generated by the national data-collection agencies and deficiencies in the existing system. These are meant to be illustrative and not exhaustive.

Some of the problems of comparability arise due to changes in scope and coverage by the national data-gathering agencies over time and space, and variations in the concepts canvassed by them. Given the structure of these agencies and the nature of their responsibilities, it would not be possible to expect that they would clean up their past data or make them comparable. This responsibility can be taken up by an apex agency created specifically for the purpose; it can attempt to achieve this, to the extent possible. The agency should build an efficient system to quickly disseminate information and be able to provide special tabulation of the data on request.

It has been noted above that the NSSO publishes much of the information on housing -- quality and construction -- at the national level. Only limited data is brought out at the state level. This makes it impossible to do any inter-regional, intra-regional or inter-city analysis. An increase in the sample size of the NSS could help generate reliable statistics on housing and basic amenities for districts and large cities. The removal of several bureaucratic and legislative constraints is urgently needed for cities to maintain their vibrant growth and attract much-needed investments in infrastructure. But this must not be done by strengthening the exclusionary character of cities wherein poor migrants are absorbed only in marginalised pockets within cities or in their degenerated peripheries. Designing this strategy requires a macro overview of the process of urban development in India which can only be built based on comprehensive information on socio-economic aspects that are comparable over time. In the absence of such a database and careful planning, interventions by public agencies will prove neither effective nor useful.

(Dr Debolina Kundu is an Associate Professor at the National Institute of Urban Affairs and has over 15 years of professional experience in the field of development studies. She has a PhD from Jawaharlal Nehru University, New Delhi. She has been engaged as a consultant with national and international organisations on issues of urban development, governance and exclusion, and is the author of several publications.This paper is based on a study, 'Concepts, Database and Methodologies for Urban Research and Action in India: Urbanisation, Urban Poverty and Slums', jointly submitted with Prof Amitabh Kundu to the Ministry of Housing and Urban Poverty-Alleviation, Government of India, 2012)


1 The Ministry of Statistics and Programme Implementation has brought out a Mid-Term Statistical Appraisal as India Country Report 2009 which assesses progress towards achieving the MDGs for the 12 targets relevant in the Indian context, out of a total of 18
2 The confusion relating to magnitude is evident from the fact that while the report quotes from various sources to stipulate that the slum population during 1991-01 ranges between 40 million and 60 million, it claims that the country has 63% and 17% shares in South Asian and global slum populations respectively, the absolute figure working out to 170 million, about three times the census figure for 2001
3 “Sometimes, the states or local bodies do not formally notify slums under their jurisdiction but they maintain a list of such areas which are officially treated as slums. All such slums have been considered along with notified sums.” Census of India (1988)
4 These are Andhra Pradesh, Bihar, Gujarat, Haryana, Jammu and Kashmir, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan, Tamil Nadu, Uttar Pradesh and West Bengal
5 ‘Notified slums’ have been defined as 'all notified areas in a town or city notified as ‘slum’ by state, UT administration or local government under any Act including a ‘Slum Act’. ‘All areas recognised as ‘slum’ by state, UT administration or local government, housing and slum boards, which may have not been formally notified as a slum under any Act’ have been defined as 'recognised slums'. ‘Identified slums’ are defined as 'a compact area of at least 300 population or about 60-70 households of poorly built congested tenements, in an unhygienic environment usually with inadequate infrastructure and lacking in proper sanitary and drinking water facilities'
6 The information has been generated annually up to the 23rd Round, excepting the 13th and 14th Rounds. All these were exploratory surveys to give broad parameters at the national level as the sample sizes were not large enough to generate estimates at the state or lower levels. It is important to note that the period of these rounds varied from six months to a year
7 Except certain areas in Jammu and Kashmir, the North East and Andaman and Nicobar Islands


Census of India (1988). Negative Aspects of Urbanisation, Census of India 1981, Occasional Paper No 3, Government of India, New Delhi

(1991) Civic and Other Amenities in the Notified Slums of Class I and II Towns, Government of India, New Delhi

(2001) Slum Census, Government of India, New Delhi

(2007) Slum Population (1,103 Towns Reporting Slums), Vol 2, Government of India, New Delhi

(2011)Housing Stock, Amenities and Assets in Slums, Government of India, New Delhi

High-Powered Expert Committee (HPEC) (2010). Report on Indian Urban Infrastructure and Services for Estimating the Investment Requirements for Urban Infrastructure Services, Government of India, New Delhi

National Sample Survey Organisation (1976). Condition of Slum Areas in Cities, July 1976-June 1977, 31st Round, Ministry of Statistics and Programme Implementation, Government of India, New Delhi

(1993) Slums in India, January-June 1993, 49th Round, Ministry of Statistics and Programme Implementation,Government of India, New Delhi

(2002) Condition of Urban Slums, July-December 2002, 58th Round, Ministry of Statistics and Programme Implementation,Government of India, New Delhi

(2009) Some Characteristics of Urban Slums, 2008-09, 65th Round, Ministry of Statistics and Programme Implementation,Government of India, New Delhi

(2012)Key Indicators of Urban Slums in India, 2012, 69th Round, Ministry of Statistics and Programme Implementation, Government of India, New Delhi, October 2014