The National Sample Survey (NSS), initiated in the year 1950, is a nation-wide, large-scale, continuous survey operation conducted in the form of successive rounds. It was established on the basis of a proposal from P.C. Mahalanobis to fill up data gaps for socio-economic planning and policy making through sample surveys. In March 1970, the NSS was reorganised and all aspects of its work were brought under a single Government organisation, namely the National Sample Survey Organisation (NSSO) under the overall direction of Governing Council to impart objectivity and autonomy in the matter of collection, processing and publication of the NSS data.