India - Household Social Consumption: Health, NSS 75th Round Schedule-25.0 :July 2017-June 2018

Sample Design

1.1 Outline of sample design: A stratified multi-stage design has been adopted for the 75th round survey. The first stage units (FSU) are the Census villages (Panchayat wards for Kerala) in the rural sector and Urban Frame Survey (UFS) blocks in the urban sector. The ultimate stage units (USU) are households in both the sectors. In the case of large FSUs, one intermediate stage of sampling is the selection of two hamlet-groups (hgs)/ sub-blocks (sbs) from each rural/ urban FSU.

1.2 Sampling Frame for First Stage Units: For the rural sector, the list of 2011 Population Census villages constitutes the sampling frame. However, for Kerala, the latest available updated list of Panchayat wards constitutes the sampling frame. For the urban sector, the latest available list of UFS blocks has been considered as the sampling frame.

1.3 Stratification:
(a) Each district is a stratum. Within each district of a State/UT, generally speaking, two basic strata have been formed: (i) rural stratum comprising of all rural areas of the district and (ii) urban stratum comprising of all the urban areas of the district. However, within the urban areas of a district, if there are one or more towns with population one million or more as per Census 2011, each of them formed as a separate basic stratum and the remaining urban areas of the district have been considered as another basic stratum. (b) In the case of rural sectors of Nagaland another special stratum has been formed within the State consisting of all the villages which are difficult to access.


1.4 Sub-stratification:

1.4.1 Rural sector: If 'r' be the sample size allocated for a rural stratum, 'r/4' sub-strata are formed in that stratum. The villages within a stratum (district) as per frame are first arranged in ascending order of population. Then sub-strata 1 to 'r/4' have been demarcated in such a way that each substratum comprises a group of villages of the arranged frame and has more or less equal population.

1.4.2 Urban sector: Each urban stratum has been divided into two parts - 'Affluent part' consisting of UFS blocks identified as 'Affluent Area' and 'Non-Affluent part' consisting of the remaining UFS blocks within the stratum. Sample allocation of a stratum is then allocated to Affluent and Non-Affluent parts in proportion to total number of households in the UFS blocks with double weightage to Affluent part subject to a maximum of 8 FSUs in 'Affluent part' of any stratum. If 'u' be the sample size allocated for an urban stratum consisting of both affluent area UFS Blocks and non affluent area UFS Blocks. 'u/4' sub-strata are formed within each stratum. Out of these 'u/4' substrata, the first two sub-strata '01' and '02' are earmarked for those UFS blocks which are identified as 'Affluent Area' and the remaining sub-strata, '03', '04',…... and so on, are assigned to the nonaffluent
UFS blocks. If any stratum does not have any Affluent Area UFS block then also the substratum number starts from '03' for that stratum. For all strata, if u/4 >1, implying formation of 2 or more sub-strata, all the UFS blocks within the stratum are first arranged in ascending order of total number of households in the UFS Blocks as per the latest UFS phase. Then sub-strata 1 to 'u/4' are demarcated in such a way that each sub-stratum has more or less equal number of households. This
procedure has been done separately for Affluent-part and Non-Affluent part of the stratum (if two sub-strata are required to be formed in the Affluent part).
The following three cases arise while doing the sub-stratification:
i) If there is no 'Affluent Area' UFS block in the stratum, all the UFS blocks are divided into 'u/4' sub-strata and numbered as '03', '04', ….., '(u/4)+2'.
ii) If only one sub-stratum is formed with the 'Affluent Area' UFS blocks, then all the
remaining non-affluent blocks are divided into '(u-4)/4' sub-strata and numbered as
'03', '04', ….., '(u/4)+1'.
iii) If two sub-strata are formed with the 'Affluent Area' blocks, then all the remaining non-affluent UFS blocks are divided into '(u-8)/4' sub-strata and numbered as '03', '04', ….., 'u/4'.


1.5 Total sample size (FSUs): 14300 FSUs have been allocated for the central sample at all-India level. For the state sample, there are 16492 FSUs allocated for all-India.

1.6 Allocation of total sample to States and UTs: The total number of sample FSUs has been allocated to the States and UTs in proportion to population as per Census 2011 subject to a minimum sample allocation to each State/UT.

1.7 Allocation of State/ UT level sample to rural and urban sectors: State/ UT level sample size has been allocated between two sectors in proportion to population as per Census 2011 with 1.5 weightage to urban sector depending on population share. A minimum of 16 FSUs (minimum 8 each for rural and urban sector separately) have been allocated to each State/ UT.

1.8 Allocation to strata: Within each sector of a State/ UT, the respective sample size has been allocated to the different strata in proportion to the population as per Census 2011. Stratum level allocation has been adjusted to multiples of 4 with a minimum sample size of 4. For special stratum formed in rural areas of Nagaland as discussed in para 1.3 (b), 12 FSUs have been allocated.

1.9 Allocation to sub-strata: Allocation for each sub-stratum has been made as 4 in both rural and urban sectors.


1.10 Selection of FSUs:

1.10.1 For the rural sector, from each stratum/sub-stratum, required number of sample villages has been selected by Probability Proportional to Size With Replacement (PPSWR), size being the population of the village as per Census 2011.

1.10.2 For the urban sector, from each stratum/sub-stratum, FSUs have been selected by Probability Proportional to Size With Replacement (PPSWR), size being the number of households of the UFS Block. Both rural and urban samples are drawn in the form of two independent sub-samples.

1.11 Selection of hamlet-groups/ sub-blocks - important steps

1.11.1 Criterion for hamlet-group/ sub-block formation: After identification of the boundaries of the FSU, it is to be determined whether listing is to be done in the whole sample FSU or not. In case the approximate present population of the selected FSU is found to be 1200 or more, it is divided into a suitable number (say, D) of 'hamlet-groups' in the rural sector and 'sub-blocks' in the urban sector
by more or less equalising the population as stated below. approximate present population of the sample FSU no. of hgs/sbs formed less than 1200 (no hamlet-group/sub-block) 1
1200 to 1799 3
1800 to 2399 4
2400 to 2999 5
3000 to 3599 6
…...and so on -
For rural areas of Himachal Pradesh, Sikkim, Andaman & Nicobar Islands, Uttarakhand (except four districts Dehradun, Nainital, Hardwar and Udham Singh Nagar), Punch, Rajouri, Udhampur, Reasi, Doda, Kishtwar, Ramban, Ladakh region (Leh and Kargil districts) of Jammu and Kashmir and Idukki district of Kerala, the number of hamlet-groups to be formed as follows:
approximate present population of the sample village no. of hgs formed
less than 600 (no hamlet-group) 1
600 to 899 3
900 to 1199 4
1200 to 1499 5
1500 to 1799 6
.….and so on -