Every survey carried out as part of the National Sample Survey (NSS) is assigned a round number. With the establishment of the NSS in the year 1950, the fieldwork of the first such survey i.e., the NSS 1st round was conducted during October 1950 to March 1951. The fieldwork for each survey/NSS round spreads over a certain duration. Most of the NSS rounds have been either of one-year duration or of six months’ duration.