India - Drinking water, sanitation, hygiene and housing condition : NSS 69th Round : July 2012- Dec 2012

1.4 Sample Design

1.4.1 Outline of sample design: A stratified multi-stage design has been adopted for the 69th round survey. The first stage units (FSU) will be the census villages (Panchayat wards in case of Kerala) in the rural sector and Urban Frame Survey (UFS) blocks in the urban sector. The ultimate stage units (USU) will be households in both the sectors. In case of large FSUs, one intermediate stage of sampling will be the selection of two hamlet-groups (hgs)/ sub-blocks (sbs) from each rural/ urban FSU.

1.4.2 Sampling Frame for First Stage Units: For the rural sector, the list of 2001 census villages updated by excluding the villages urbanised and including the towns de-urbanised after 2001 census (henceforth the term 'village' would mean Panchayat wards for Kerala) will constitute the sampling frame. For the urban sector, the latest updated list of UFS blocks (2007-12) will be considered as the sampling frame.

1.4.3 Stratification: Within each district of a State/ UT, generally speaking, two basic strata will be 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 10 lakhs or more as per population census 2011 in a district, each of them will form a separate basic stratum and the remaining urban areas of the district will be considered as another basic stratum.

In case of rural sectors of Nagaland and Andaman & Nicobar Islands, the coverage has been extended to the entire State/UT from this round. In these two State/UTs, one separate special stratum will be formed within the State/UT consisting of all the interior and inaccessible villages which were not covered in previous rounds.

1.4.4 Sub-stratification:

Rural sector r: If 'r' be the sample size allocated for a rural stratum, the number of sub-strata formed will be 'r/2'. The villages within a district as per frame will be first arranged in ascending order of population. Then sub-strata 1 to 'r/2' will be demarcated in such a way that each sub-stratum will comprise a group of villages of the arranged frame and have more or less equal population.

Urban sector: Each stratum will be divided into 2 sub-strata as follows:

sub-stratum 1: all UFS blocks having area type 'slum area'
sub-stratum 2: remaining UFS blocks

1.4.5 Total sample size (FSUs): 8000 FSUs will be surveyed for the central sample at all-India level. For the state sample, there will be 9112 FSUs for all-India. In addition to this, some more sample FSUs (in the form of sub-sample 3) will be allocated exclusively for slum schedule. State wise allocation of sample FSUs is given in Table 1, page A-16.

1.4.6 Allocation of total sample to States and UTs: The total number of sample FSUs will be allocated to the States and UTs in proportion to population as per census 2011 subject to a minimum sample allocation to each State/ UT. While doing so, the resource availability in terms of number of field investigators as well as the comparability with previous round of survey on the same subjects will be kept in view.

1.4.7 Allocation of State/ UT level sample to rural and urban sectors: State/ UT level sample size will be allocated between two sectors in proportion to population as per census 2011 with double weightage to urban sector subject to the restriction that urban sample size for bigger states like Maharashtra, Tamil Nadu etc. should not exceed the rural sample size. A minimum of 16 FSUs (minimum 8 each for rural and urban sector separately) will be allocated to each state/ UT.


1.4.8 Allocation to strata: Within each sector of a State/ UT, the respective sample size will be allocated to the different strata in proportion to the population as per census 2011 wherever the information is available, failing which information on population as per census 2001 will be used. Allocations at stratum level will be adjusted to multiples of 2 with a minimum sample size of 2.

For special stratum in Nagaland and A & N Islands, 8 FSUs will be allocated to each.

1.4.9 Allocation to sub-strata:

1.4.9.1 Rural: Allocation will be 2 for each sub-stratum in rural.

1.4.9.2 Urban: Stratum allocations will be distributed among the two sub-strata in proportion to the number of FSUs in the sub-strata. Minimum allocation for each sub-stratum will be 2. Equal number of samples will be allocated among the two sub-rounds.

Also, an additional sample of FSUs in the form of sub-sample 3, equal to number of sample FSUs in each of the sub-samples 1 & 2 in the sub-stratum 1 only, will be allocated.

1.4.10 Selection of FSUs:

For the rural sector, from each stratum/ sub-stratum, required number of sample villages will be selected by probability proportional to size with replacement (PPSWR), size being the population of the village as per Census 2001.

For the urban sector, UFS 2007-12 phase will be used for all towns and cities and from each stratum/sub-stratum FSUs will be selected by using Simple Random Sampling Without Replacement (SRSWOR).

Both rural and urban samples are to be drawn in the form of two independent sub-samples and equal number of samples will be allocated among the two sub rounds. For urban sub-stratum 1, additional samples will be drawn in the form of sub-sample 3 independently.

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

1.4.11.1 Proper identification of the FSU boundaries: The first task of the field investigators is to ascertain the exact boundaries of the sample FSU as per its identification particulars given in the sample list. For urban samples, the boundaries of each FSU may be identified by referring to the map corresponding to the frame code specified in the sample list.

1.4.11.2 Criterion for hamlet-group/ sub-block formation: After identification of the boundaries of the FSU, it is to be determined whether listing will 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 will be 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 hg's/sb's to be formed

less than 1200 (no hamlet-groups/sub-blocks) 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, Uttarakhand (except four districts Dehradun (P), Nainital (P), Hardwar and Udham Singh Nagar), Poonch, Rajouri, Udhampur, Doda, Leh (Ladakh), Kargil districts of Jammu and Kashmir and Idukki district of Kerala, the number of hamlet-groups will be formed as follows:

approximate present population of the sample village no. of hg's to be formed

less than 600 (no hamlet-groups) 1
600 to 899 3
900 to 1199 4
1200 to 1499 5
1500 to 1799 6
.………..and so on .

1.4.11.3 Formation and selection of hamlet-groups/ sub-blocks: In case hamlet-groups/ sub-blocks are to be formed in the sample FSU, the same should be done by more or less equalizing population. Note that while doing so, it is to be ensured that the hamlet-groups/ sub-blocks formed are clearly identifiable in terms of physical landmarks.

Two hamlet-groups (hg)/ sub-blocks (sb) will be selected from a large FSU wherever hamlet-groups/ sub-blocks have been formed in the following manner - one hg/ sb with maximum percentage share of population will always be selected and termed as hg/ sb 1; one more hg/ sb will be selected from the remaining hg's/ sb's by simple random sampling (SRS) and termed as hg/ sb 2. Listing and selection of the households will be done independently in the two selected hamlet-groups/ sub-blocks. The FSUs without hg/ sb formation will be treated as sample hg/ sb number 1. It is to be noted that if more than one hg/ sb have same maximum percentage share of population, the one among them which is listed first in block 4.2 of schedule 0.0 will be treated as hg/ sb 1.

1.5 Listing of households: Having determined the hamlet-groups/ sub-blocks, i.e. area(s) to be considered for listing, the next step is to list all the households (including those found to be temporarily locked after ascertaining the temporariness of locking of households through local enquiry). The hamlet-group/ sub-block with sample hg/ sb number 1 will be considered for listing first, to be followed by the listing of households within the sample hg/sb number 2.

1.6 Formation of second stage strata and allocation of households


1.6.1 Two cut-off points 'A' and 'B' (in `) have been determined from NSS 66th round data for each NSS region for urban areas in such a way that top 10% of the population have MPCE more than 'B' and bottom 30% of the population have MPCE less than A. The values of A and B for each NSS Region have been given in Chapter two.

1.6.2 Households listed in the selected FSU/ hamlet-group/ sub-block will be stratified into three second stage strata (SSS). Composition of the SSS and number of households to be surveyed from different SSS will be as follows:

SSS composition of SSS number of households to be surveyed
FSU without hg/sb formation FSU with hg/sb formation (for each hg/sb)
Rural

SSS 1: households having pucca dwelling structure 4 2
SSS 2: households having semi-pucca dwelling structure 4 2
SSS 3: other households (including those with no structure) 4 2
Urban

SSS 1: households having MPCE of top 10% of urban population (MPCE > B) 2 1
SSS 2: households having MPCE of middle 60% of urban population (A = MPCE = B) 4 2
SSS 3: households having MPCE of bottom 30% of urban population (MPCE < A) 6 3

1.6.3 The above table provides the plan of allocation of the sample household in the respective SSS. However, there can be situations in the selected FSUs both in rural and urban sectors where adequate number of households is not available for required allocation. In such situation, the selection of household for the SSS is compensated from the other SSS. This is done by adopting specified procedure. To meet the shortfall of households in one SSS compensation can be made from other SSSs. The details of the compensation rules are given in the Chapter two dealing with Schedule 0.0.


There was no deviation from the original sample deviation.