NSSO has been conducting multi-subject integrated sample surveys all over the country in the form of successive rounds relating to various aspects of social, economic, demographic, industrial and agricultural statistics. In order to strike a balance between the urgent need for the data on wide variety of topics and the constraint of the limited resources, both financial and others, the NSS from its very inception has been following a multi-subject integrated survey system. In this system several subjects of enquiry, not necessarily closely related, are simultaneously taken up in a single survey operation to optimise the use of resources, to effect economy and operational convenience and also to achieve better analysis of the survey results.

The subject coverage of SE inquiries for different rounds is decided on the basis of a 10 year time frame. In this cycle, 1 year is devoted to land and live stock holdings, debt and Investment; 1 year to social consumption ( education and health care, etc. ), 2 years to quinquennial surveys on household consumer expenditure, employment & un-employment situation and 4 years to non- agricultural enterprises, namely, manufacturing, trade and services in un-organised sector. The remaining 2 years are for open rounds in which subjects of current/special interest on the demand of Central Ministries, State Governments and research organizations are covered.

Each survey extends over a period of a few months or a year which is termed a round. At present each NSS round covers, at the all India level, about 12,000 to 14,000 villages and urban blocks in the Central sample (covered by the Central government agency NSSO) and an independent sample of about 14,000 to 16,000 villages and blocks in the State sample (covered by the Governments of various states and union territories).

The Socio-Economic Surveys cover the whole of the Indian Union except for a few inaccessible and difficult pockets.