Definition
The xhpsu stands for primary sampling unit(PSU) in the sample. A PSU is the sampling unit representing a ward or combination of wards or sub-ward in case of larger population count wards.
The NLSS3 sample consists of 500 cross-sectional and 100 panel PSUs. The 100 panel PSUs in NLSS3 consist of 50 PSUs each from panel and cross-sectional component of NLSS2 sample. Therefore, the each half of panel PSUs in the current survey represents PSUs from both of NLSS1 and NLSS2.
The PSU number from 1 to 500 denotes the panel sample from NLSS1, from 501 to 1000 denotes panel sample from NLSS2 and from 1001 onwards represents the cross-sectional sample of NLSS3.