National Sample Survey Office (NSSO)
National Sample Survey Office (NSSO) Statistical System In India Ministry of Statistics and Programme Implementation (MoS&PI) MOS&PI has two Wings I. Statistics Wing - National Statistical Organization (NSO) Central Statistics Office (CSO) National Sample Survey Office (NSSO) II. Programme Implementation Wing Statistical System In India • Central Statistical Office (CSO): The main responsibility assigned to the CSO is to bring about coordination of statistical activities among various statistical agencies in the Central Government and of Statistical Bureaus of State Governments, which were set up for similar coordination of activities of statistical agencies at the State level. • National Sample Survey Office (NSSO): The main responsibility assigned to the NSSO is to collect data on varied Socio-Economic subjects through nation-wide sample surveys to create and update data base. National Sample Survey Office (NSSO) • The Directorate of National Sample Survey (NSS) came into being in 1950 to collect information through sample surveys on a variety of socio-economic aspects. • The Directorate of NSS was assigned the job of conducting the field work. • The work relating to finalisation of sampling design, schedules of enquiries, writing of instructions, training of field staff, processing of data and writing of reports was all entrusted to the Indian Statistical Institute. National Sample Survey Office (NSSO) • In March 1970, the Directorate of NSS was reorganised and all aspects of its work were brought under a single government organization called National Sample Survey Organisation (NSSO) under the overall technical guidance of Governing Council. • After the formation of National Statistical Commission (NSC) on 01.06.2005, the Governing Council of NSSO was dissolved and its work was taken over by NSC. NSC constitution • Chairman: Eminent statistician or social scientist. • Part time members: 4 part time members having experience in (i) Economic Statistics., (ii) Social and Environment Statistics., (iii) Statistical Operations such as Census/ Surveys • The Secretary, Planning commission (ex-officio member) • CSI. THE PRESENT STRUCTURE Ministry of Statistics& Programme Implementation National Statistical Commission NSSO SDRD FOD DPD CPD National Sample Survey Office Basic Objective: Collection of data on varied Socio-Economic subjects through nation-wide sample surveys to create and update data base for use in: -Policy formulation -Programme implementation -Programme evaluation -Research & public debate and -Economic & administrative decisions for national development. Organisational Structure • The NSSO is headed by the DG & CEO. • It is the largest survey organization of its kind with staff strength of about 5288 comprising 269 group A officers and 5019 other officials. • The organisation has four divisions: – Survey Design and Research Division (SDRD) – Field Operations Division (FOD) – Data Processing Division (DPD) – Coordination & Publication Division (CPD) (Earlier called Economic Analysis Division) NSC and National Sample Surveys (NSS) • The NSSO functions under the overall guidance of the NSC and the Working groups constituted by it for each Round of S.E. surveys. • The NSC decides – Short and long term programmes including subjects to be covered and periodicity – Methodological improvements in conduct of surveys • Approves sample design, concepts and definitions, questionnaires, estimation procedure, tabulation plan, etc. • Approves studies for improving survey methodology, data collection, processing and dissemination and other issues . • Approves the survey reports for release • Constitute Expert Groups for any specific technical issue, if necessary Schedule of Surveys Ten Year Cycle Consumer Expenditure and Employment & Unemployment - Twice Social Consumption (health, education etc.) (generally 6 month survey) - Twice Un-organised Manufacturing - Twice Services Sector - Twice - Once Land & Livestock holdings and Debt & Investment Open Round - Two years (For other surveys on demand) Survey Design And Research Division (SDRD) Located at Kolkata and headed by Addl. Director General Major Functions Formulation of sampling design, concepts and definitions Drawing of survey schedules Instruction Manuals for field work Finalisation of Sample List Scrutiny and validation instructions i.e. FSP, PDES, CSP, HOWLER Pts. etc. Checking of Multipliers, draft tables Formulation of Tabulation plan Drawing up of Estimation Procedure Finalisation of survey results & Preparation of key reports Undertaking studies for the improvement of survey methodology Publication and distribution/ sale of NSS reports, Providing technical guidance on sampling techniques to various official agencies, etc. • Secretarial assistance to the Working Group on NSS surveys • • • • • • • • • • • • Field Operations Division (FOD) of NSSO Hqrs. at New Delhi and Faridabad and headed by an Addl. Director General. The biggest Division of NSSO having a network of 175 offices spread throughout the length and breadth of the country at 3-levels, viz.: 6 Zonal Offices 49 Regional Offices 118 Sub-regional Offices Responsible for carrying out the field work of not only the Socio-economic surveys but also for other surveys. Activities of FOD Besides carrying out the field work of Socioeconomic surveys, the FOD is also responsible for: Carrying out the field work of Annual Survey of Industries (ASI) on behalf of CSO; Carrying out the supervision of agricultural surveys conducted by State Agricultural Statistical Authorities (SASA), on area enumeration and crop cutting experiments; Collection of Price Data for Consumer Price Index (Urban) from Urban Centers, on behalf of CSO; Collection of price data from rural centers for CPI for Agricultural/ Rural Labourers compiled by Labour Bureau; and Carrying out the Urban Frame Survey (UFS), for a frame for urban areas for Socio-economic surveys. Field Problems in SE Survey Length of schedules resulting in informant/ investigator fatigue Arduous field conditions Informants’ indifference/ reluctance Informants tend to hide their income and exaggerate their expenditure Investigators are posted at a place where local people’s language is not known to the Investigator To manage with contract investigators due to large no. of vacancies in regular posts Data Processing Division (DPD) Located at Kolkata and headed by Addl. Director General Major Functions To undertake data-processing and tabulation for various NSS rounds and other adhoc surveys. • To provide technical assistance to the SSBs/ DESs for processing and tabulation of NSS State sample data and also for pooling central and state sample data. • To impart training on IT and data processing. • To undertake special tabulation work for Ministries/ Govt. Departments. Activities of Data Processing -Finalisation of sampling frame in consultation with SDRD -Software development for generation of sample list as per the design and drawing sample as per allocation -Software development for data entry, verification and validation for central and state sample -Training Manual preparation (system design, data layout, PDES and CSP points) -PDES inconsistencies taken up with FOD -Phase-I validation, CSP (Content check) -Phase-II validation (Coverage check) -Phase-III validation (Howler check) -Software for estimation procedure and computation of multiplier -Generation of trial and final tables -Dissemination of unit level data Coordination & Publication Division (CPD) Located at New Delhi and headed by a Dy. Director General • Functions as technical secretariat for DG&CEO • CPD is responsible for: – Coordinating the activities of all the four divisions of NSSO – Dissemination of survey results – Publication of the biannual technical journal "Sarvekshana". – Supplying survey data of various rounds to individuals, research scholars, research Institutions and other private and government bodies – Liaison with other Departments/Ministries on various matters concerning NSSO. – Dealing with Parliament questions. Different Activities during one Round of NSS • • • • • Deciding subject and formation of Working Group (WG) WG deliberations – Subject coverage, concepts and definitions, sampling design, draft survey instruments Finalisation of survey instruments – Training manual and survey instruments , – AITOT – Sample selection and dissemination of Sample List (Central and State sample) – Tabulation plan and estimation procedure – Quality control instruments • FSP, PDES, CSP, • Consolidated clarification on field queries post RTC • Reply of queries from field offices of FOD & DES on regular basis. Data validation – Computer Edit Programme (CEP), Trial tables, Final tables Report finalisation and Dissemination – First draft, in-house discussion, 2nd draft, draft circulation, assimilation of comments, approval by NSC – printing, press release, release of report – Dissemination, sale and documentation Subjects Coverage in recent Past NSS 71st round (Jan - June, 2014) 1.Social Consumption: Health and Education NSS 70th round (Jan - Dec, 2013) 1. Land & Livestock holdings and Debt & Investment 2. Situation Assessment of Farmers NSS 69th Round (July - Dec, 2012) 1. Housing conditions, Drinking Water Supply & Sanitation and Hygiene NSS 68th round (July, 2011 - June, 2012) 1. Employment & Unemployment 2. Household Consumer expenditure NSS 67th Round (July, 2010 - June, 2011) 1.Unincorporated non-agricultural enterprises in manufacturing, trade and other services sector (excluding construction) Subject coverage for current round NSS 72nd round (Jul 2014 - Jun 2015) Consumer Expenditure, Domestic Tourism and Household Consumption of Durable Goods and Services Data Users • • • • • • • Planning Commission - Employment & Unemployment and Household Consumer Expenditure. National Accounts Division, CSO - Employment & Unemployment, Household Consumer Expenditure, Unorganised Manufacturing, Unorganised Services, Debt & Investment. Reserve Bank of India - Debt & Investment. Ministry of Labour - Employment & Unemployment. Various other Ministries & Departments (Health, Education, Women & Child Development etc.) - Socio Economic Surveys, Land & Livestock Holdings etc. Research Scholars (worldwide). UN Agencies (IMF, UNICEF, FAO etc.) Basic Concepts of Survey Sampling Theory 1 Statistical Survey Sampling Statistical Survey Sampling is a systematic approach to selecting a few elements (a sample) from an entire collection of data (a population) in order to make some inferences about the total population. The sampling methods help us to ensure that samples represent the entire population. A sample of fairly modest size is sufficient to give a reasonable idea of a much larger universe. 2 Advantages of Survey Sampling less expensive timeliness wider range of survey data wider choice of methods of observation, measurement or questioning results subject to smaller non-sampling errors 3 Disadvantages of Survey Sampling results of a sample survey are subject to sampling errors. a sample may seriously over-represent, under-represent, or even fail to represent infrequently-occurring subgroups of a population. results at disaggregated levels may not be reliable. 4 Principal Steps in a Sample Survey 1. Objective of the Survey 2. Defining the Population to be Sampled 3. The Frame and Sampling Units 4. Selection of Proper Sampling Design 5. Data to be collected 6. The Questionnaire or Schedule 5 Principal Steps in a Sample survey (contd.) 7. Method of Collecting Information (i) Interview Method (ii) Mailed Questionnaire Method 8. Organisation of field Work 9. Treatment of non-response 10. The Pretest 11. Summary and Analysis of the Data (i) Scrutiny and editing of the data (ii) Tabulation of data (iii) Statistical analysis (iv) Reporting and conclusions 6 Sampling and Non-sampling Errors 7 The theory of survey sampling includes a variety of sample selection and estimation methods its objective is to obtain a reasonably representative sample Methods of Sampling – three broad categories The three broad categories of methods of sampling are (a) Non-probability sampling – Subjective or purposive or judgment sampling (b) Probability sampling (c) Mixed Sampling 9 Sample Design specifies i. ii. iii. iv. v. vi. vii. viii. ix. the population to be surveyed, sample units to adopt and different stages of selection if required sample selection method, sampling frame to use (list of units, maps of area), size of the sample, stratification, allocation of size to different strata, statistic to be used treatment of non-response estimation procedure of sampling error. Sample Selection Procedures / Schemes Some of the common selection methods of sample are: a. Simple Random Sampling b. Systematic Sampling c. Stratified Sampling d. Cluster Sampling e Probability Proportional-to-size Sampling f. Multi-stage sampling. 11 Stratified Sampling In this sampling procedure, we divide the population into relatively homogeneous groups called Strata. Then from each stratum randomly select a specified number of elements using any of the following two criteria: Proportional allocation Optimum allocation Greater the difference in the stratum means, greater is the gain in precision of stratified sampling over un-stratified simple random sampling. 12 Allocation of Sample size In proportional Allocation ni = (n/N)*Ni Or n1/N1 = n2/N2 ………= nk/Nk = n/N In optimum allocation ni’s are chosen so as to (a) Maximise the precision for (i) fixed sample size n or (ii) fixed cost (b) Minimise the total cost for fixed precision 13 Advantages of Stratified Random Sampling (i) More representative (ii) Greater accuracy (iii) Administrative convenience (iv) Very useful in the fields of highly skewed distributions 14 Multistage Sampling As the name suggests, multistage sampling refers to a sampling technique, which is carried out in various stages. Example: If we are interested in obtaining a sample of households from rural areas of a particular State, the first stage units may be districts, the second staged units may be villages in the districts and third stage units will be households in the villages. Each stage thus results in a reduction of the sample size. Contd…. • Multistage sampling consists of sampling first stage units by some suitable method of sampling. • From among the selected first stage units, a sub-sample of secondary stage units is drawn by some suitable method of sampling which may be same as or different from the method used in selecting first stage units. • Further stages may be added to arrive at a sample of the desired sampling units. Merits and Limitations of Multistage sampling • Multistage sampling is more flexible as compared to other methods of sampling. • It is simple to carry out and results in administrative convenience by permitting the field work to be concentrated, yet covering large area. • Most practical advantage of multistage sampling is that we need the second stage frame only for those units which are selected in the first stage sample. • This leads to great saving in operational cost. • However, a multistage sampling is generally less efficient than a suitable single-stage sampling of the same size. Sampling Design used in Socio-economic Surveys undertaken by NSSO A stratified multi-stage sampling design is generally used in Socio-economic Surveys undertaken by NSSO. The first stage units (FSU) are 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) are households in both Rural & Urban Sectors. In case of large FSUs, one intermediate stage of sampling is done by selecting two hamlet groups/ sub blocks from each of such rural/ urban FSU respectively. 18 NSS 72nd ROUND (July 2014 – June 2015) ‘Consumer Expenditure’ ‘Domestic Tourism Expenditure’ ‘Household Expenditure on Services and Durable Goods’ Sample Design 1 Schedules of enquiry Schedule 0.0 List of Households Schedule 1.60 Household Consumer Expenditure (4) Schedule 1.61 Household Consumer Expenditure with details of Food Consumption (4) Schedule 1.62 Household Consumer Expenditure with details of Non-Food Consumption (4) Domestic Tourism Expenditure (10) Schedule 21.1 Schedule 1.5 Sample Design Household Expenditure on Services and Durable Goods (6) 2 Coverage and sample design Sample Design 3 Geographical coverage Whole of the Indian Union except the villages in Andaman and Nicobar Islands which remain extremely difficult to access due to the restriction imposed by local authorities Sample Design 4 Participation of States/ UTs State/UT Nagaland (U) Sample Design Extent of matching triple Andhra Pradesh, J & K , Manipur, Odisha, Delhi double Maharashtra (U) one and half Remaining States/ UTs equal 5 Work Programme and Sub-rounds The survey will be of one year duration starting from 1st July 2014 and ending on 30th June 2015. Survey period will be divided into four sub-rounds of three months’ duration each, as follows: sub-round 1 : July - September 2014 sub-round 2 : October - December 2014 sub-round 3 : January - March 2015 sub-round 4 : April - June 2015 Sample Design 6 Work Programme and Sub-rounds Sample Design In each of these four sub-rounds equal number of sample villages/ blocks (FSUs) will be allotted for survey. Because of the arduous field conditions, this restriction is not strictly enforced in Andaman and Nicobar Islands, Lakshadweep, Leh (Ladakh) and Kargil districts of Jammu & Kashmir and rural areas of Arunachal Pradesh and Nagaland. 7 Sample Design - Outline A stratified multi-stage design will be adopted for the 72nd round survey. First Stage Units (FSU) – 2011 Census list of villages in the rural sector Urban Frame Survey (UFS) blocks (UFS 2007-12 Phase) in the urban sector In case of large FSUs, hamlet-groups (hg’s) in rural areas and sub-blocks (sb’s) in urban areas will form the intermediate stage units. The ultimate stage units (USU) will be households in both the sectors. Sample Design 8 Total sample size (FSUs) 14088 FSUs are allocated for central sample at all-India level. ◦ 8016 for Rural Sector ◦ 6072 for Urban Sector Sample Design 9 Allocation – central sample Sample Design Allocation of total sample to States/UTs: Proportional to State/UT population as per Census 2011. A minimum of 16 FSUs (minimum 8 each for rural and urban sectors separately) will be allocated to each State/ UT. State/ UT level sample size is to be allocated between two sectors in proportion to population as per Census 2011 with double weightage to urban sector. 10 Stratification Within each district of a State/UT, two basic strata will be formed: ◦ (i) rural stratum comprising all rural areas of the district and ◦ (ii) urban stratum comprising all the urban areas of the district. Sample Design 11 Sub-stratification - Rural Sample Design If ‘r’ be the sample size allocated for a rural stratum, the number of sub-strata formed will be ‘r/4’. The villages within a district as per frame will be first arranged in ascending order of population. Then sub-strata 1 to ‘r/4’ 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. 12 Sub-stratification - Urban Sample Design Let, ‘u’ be the sample size allocated for an urban stratum ‘u/4’ sub-strata will be formed within each stratum UFS blocks identified as ‘Affluent Area’ within the stratum is made separate sub-strata 13 Sub-stratification – Urban (contd.) Sample Design if there is no ‘Affluent Area’ block in the stratum, all the UFS blocks will be divided into ‘u/4’ sub-strata if only one sub-stratum is formed with the ‘Affluent Area’ blocks, then all the remaining non-affluent blocks will be divided into ‘(u-4)/4’ sub-strata if two sub-strata are formed with the ‘Affluent Area’ blocks, then all the remaining non-affluent blocks will be divided into ‘(u-8)/4’ sub-strata 14 Sub-stratification – Urban (contd.) Sample Design All the UFS blocks within the stratum will be first arranged in ascending order of total number of households in the UFS Blocks as per UFS phase 2007-12 Sub-strata will be demarcated in such a way that each sub-stratum will have more or less equal number of households The above procedure will be followed separately for ‘affluent’ and ‘non-affluent’ part of the stratum 15 Allocation to strata and sub-strata Allocations at stratum level will be adjusted to multiples of 4 with a minimum sample size of 4. For both rural and urban stratum, allocation will be 4 for each sub-stratum. Sample Design 16 Selection of FSUs Rural sector - Probability Proportional to Size With Replacement (PPSWR), size being the population of the villages as per Census 2011. Urban sector - Probability Proportional to Size With Replacement (PPSWR), size being the number of households of the UFS blocks as per UFS phase 2007-12. Equal number of samples will be allocated among the four sub rounds. Sample Design 17 Usual criterion for hamlet-group/ sub-block formation Selected FSUs with approximate population 1200 or more will be divided into a suitable number of ‘hamlet-groups’ in the rural sector and ‘sub-blocks’ in the urban sector with more or less equal population. Sample Design 18 Usual criterion for hamletgroup/ sub-block formation approximate present population no. of hg’s/sb’s to be formed of the sample FSU Sample Design less than 1200 1 1200 - 1799 3 1800 - 2399 4 2400 - 2999 5 3000 - 3599 6 …..and so on - 19 For rural areas of Himachal Pradesh, Sikkim, Andaman & Nicobar Islands, Uttarakhand (except four districts Dehradun, Nainital, Hardwar and Udham Singh Nagar), Poonch, Rajouri, Udhampur, Reasi, Doda, Kistwar, Ramban, Leh (Ladakh), Kargil districts of Jammu and Kashmir and Idukki district of Kerala approximate present population of the sample FSU less than 600 600 - 899 900 - 1199 1200 - 1499 1500 - 1799 …..and so on Sample Design no. of hg’s to be formed 1 3 4 5 6 20 Selection of hamlet-groups/ sub-blocks Sample Design Formation of hg/sb: By equalizing population maintaining geographical contiguity. Two hg’s/ sb’s will be selected: • The hg/sb with the largest percentage share of population will always be selected and termed hg/sb 1; • one more hg/sb will be selected from the remaining hg’s/sb’s by Simple Random Sampling (SRS) and termed hg/sb 2. Listing and selection of the households will be done independently in the two selected hamlet-groups/ sub-blocks. 21 Selection of households From each selected FSU and hg/sb, the sample households for each of the schedules will be selected by SRSWOR. Sample Design 22 Sample Design 23
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