NSSO surveys along India’s periphery : data quality and its implications

Azim Premji University,


Sample surveys conducted by the National Sample Survey Office (NSSO) are the most widely used sources of household level information about consumption, employment, and other socio-economic indicators in India. The representativeness of samples, the wide range of topics surveyed, and the availability of a long-time series are some of the reasons for the appeal of NSSO data for research and policy. This paper assesses the quality of the NSSO data for Nagaland and Jammu and Kashmir, which lie in India’s politically restive ethno-geographical periphery. It argues that the NSSO data for these states during 1973 – 2014 lack representativeness and inter-temporal comparability due to faulty sampling frames, frame and sample non-coverage, and biased samples. It quantifies the impact of data quality on statistics of interest to policy-makers. The paper shows that the estimates of monthly per capita consumption expenditure (MPCE) are sensitive to non-coverage and argues that the incidence of poverty is underestimated because NSSO surveys failed to capture the complete distribution of consumption expenditure due to non-coverage. In Nagaland, the degree of non-coverage was so high that in most years between 1993 – 94 and 2011-12 the state’s poverty headcount ratio was the lowest in the country despite the possible overestimation of its poverty line. The paper concludes with a discussion of the implications of the use of non-representative survey data. Put together, the unreliability of government statistics in Jammu and Kashmir and Nagaland highlights systemic problems that have wider implications for our understanding of the relationship between state, statistics, and policy-making.