Organization: Hellenic Statistical Authority
Οrganization unit: Population and Labour Market Statistics Division
Name: Zachariou Stylianos
Person function: Head of Labour Force Survey Section
Mail address: 46 Pireos and Eponiton Str 185 10 PIRAEUS
E-mail address: [email protected]
Phone number: (+30) 2104852173
Fax number: (+30) 2104852948

Labour Force Survey is the main source of data on employment and unemployment. It is a continuation of the former “Employment Survey” which had been conducted in the urban and semi urban areas of the country in years 1974-1980. In 1981 Labour Force Survey was conducted covering the whole of the country for the first time. It followed the same specifications with similar surveys running in the then EEC member countries. Until 1997 the survey was conducted every year in the second quarter. From 1998 onwards the survey is carried out throughout the year and is designed to produce results on a quarterly basis. Besides data on employment and unemployment also collects information on demographic characteristics, level of education and participation in educational activities.

Last certified: September 2016
Last posted: September 2016
Last updated: September 2016

Data description: The main statistical objective of the Labour Force Survey is to divide the population of working age (15 years and above) into three mutually exclusive and exhaustive groups - persons in employment, unemployed persons and inactive persons. In addition, Labour Force Survey collects information on: demographic characteristics, main job characteristics, the existence and characteristics of a second job, educational attainment, participation in education, previous working experience and on search of job.
Classification system: Economic activity, until 2007, was classified according to STAKOD 03 (ΣΤΑΚΟΔ 03) which is the Greek version of NACE Rev1.1. From 2008 onwards STAKOD 08 (ΣΤΑΚΟΔ 08) is used, which is identical (at 3 - digit level) to NACE Rev2. The classification is based on the 3-digit level for the main job,and on the 2-digit level for the second and previous job. Occupation, until 2011, was classified according to STEP-92 (ΣΤΕΠ-92), which is the Greek version of the International Standard Classification of Occupations - ISCO-88 (Com). From 2011 onwards, ISCO-08 is used. Classification is based on the 3-digit level for the main, second and previous job. Nationality and Country of birth are classified according to a specific classification used for the Labour Force Survey. Level of education is classified according to a specific classification used for the Labour Force Survey, which allows for the classification of educational level according to International Standard Classification of Education (ISCED 11). Field of education is classified according to ISCED 11 at 1 digit level (2 and 3 digits are used for special fields in science, and foreign languages) . Geographical areas are classified according to NUTS classification.
Sector coverage: LFS is a household survey
Statistical concepts and definitions: Employed are persons aged 15 years or older, who during the reference week had worked, even for just one hour, for pay or profit or they have worked in the family business, or they were not at work but had a job or business from which they were temporarily absent. Unemployed are persons aged 15-74 who were without work during the reference week (they were not classified as employed), were currently available for work and were either actively seeking work in the past four weeks or had already found a job to start within the next three months. Inactive are those persons who neither classified as employed nor as unemployed. Self-employed with employees are persons who work in their own business, professional practice or farm for the purpose of earning a profit, and who employ at least one other person. Self-employed person without employees are persons who work in their own business, professional practice or farm for the purpose of earning a profit, and who employ no other persons. Employees are defined as persons who work for a public or private employer and who receive compensation in the form of wages, salaries, fees, gratuities, payment by results or payment in kind. Family workers are persons who help another member of the family to run a farm or other business, provided they are not classified as employees (they are not receiving a salary, and they have not a direct profit from the business). Part-time job , Full-time job. The distinction between these two forms of job is based on the spontaneous response of the respondent to a relevant question. Temporary job. A job may be considered temporary if the employer and the employee agree that the termination of the job is determined by objective conditions such as a specific date, the completion of a task or the return of another employee who has been temporarily replaced. This agreement is not necessarily based on a written work contract. Duration of unemployment is defined as the duration of search for a job, or the length of the period since the last job was held (if this period is shorter than the duration of search for a job). Persons in education. A person is considered in education if he/she is following any educational program, including initial education, additional education, vocational education, continuing or additional training, training in enterprises, apprenticeships, on-the-job training, seminars and workshops, distance education, evening classes, self-learning, etc. Also are included courses for personal interest only, which may cover all forms of learning, and training in subjects such as languages, computer studies, business studies, art and culture, health and medicine.
Statistical unit: Households, persons
Statistical population: Population residing in private households, and staying (or intend to stay) at least 1 year in Greece. Individuals who permanently reside in collective houses (i.e. hospitals, hotels, asylums, homes for the elderly, orphanages, etc) are not covered by the survey.
Reference area: All NUTS 3 areas of Greece, with the exception of Mount Athos area
Time coverage: Labour Force Survey has been producing results since 1981 on a yearly basis (spring quarter). From 1998 onwards it is a continuous survey, providing quarterly results.
Base period: There is no base period in Labour Force Survey

Number of persons, %, mean, years (age), hours (of work, education)

The Labour Force Survey’s sample is spread uniformly in the 13 (or 14) weeks of the quarter. Every sampled household corresponds to a particular week, namely the reference week (from Monday to Sunday). • For employment, the reference period is the reference week. • For job search, working time arrangements, and participation in education, the reference period is the four- week period, ending with the reference week. • For availability to start, or resume, a job the reference period is the two-week period after the reference week. For monthly estimates, the sample used is the sample that is allocated in the four (or five) reference weeks of the particular month,. When the days of a week belong to two different months, this week is considered to belong to the month that includes that Thursday of the particular week

Legal acts and other agreements: Hellenic Statistical Authority is an independent authority responsible for the production and dissemination of official statistics. The legal framework concerning the organization and operation of ELSTAT is as follows: ■ Law 3832/2010 (Government Gazette No 38, Issue Α): “Hellenic Statistical System Establishment of the Hellenic Statistical Authority (ELSTAT) as an Independent Authority”, as amended by article 90 paragraphs 8 and 9 of the Law 3842/2010 (Government Gazette No 58, Issue Α): “Restoration of fiscal justice, confrontation of tax evasion and other provisions”, by article 10 of the Law 3899/2010 (Government Gazette No 212, Issue A): “Urgent measures for the implementation of the assistance program of the Greek Economy”, by article 45 of the Law 3943/2011 (Government Gazette No 66, Issue A): “Combating tax evasion, staffing of auditing services and other provisions falling within the competence of the Ministry of Finance”, by article 22 paragraph 1 of the Law 3965/2011 (Government Gazette No 113, Issue A): “Operations Reform of the Consignment and Loan Fund, Public Debt Management Agency, Public Enterprises and Government bodies, the establishment of the General Secretary of Public Property and other provisions” and by article 51 of the Law 4021/2011 (Government Gazette No 218, Issue A): “Enhanced measures for the supervision and restructuring of Credit Institutions – Regulation of issues of financial nature – Ratification of the European Financial Stability Facility (EFSF) Framework-Agreement and its amendments and other provisions.” ■ Regulation (EC) No 223/2009 of the European Parliament and of the Council, on the European statistics (Official Journal of the European Union L 87/164). ■ Article 14 of the Law 3470/2006 (Government Gazette No 132, Issue A): “National Export Council, tax regulations and other provisions”. ■ Article 3, paragraph 1c, of the Law 3448/2006 (Government Gazette No 57, Issue A): “For the further use of information coming from the public sector and the settlement of matters falling within the responsibility of the Ministry of Interior, Public Administration and Decentralization”. ■ European Statistics Code of Practice, adopted by the Statistical Programme Committee on 24 February 2005 and promulgated in the Commission Recommendation of 25 May 2005 on the independence, integrity and accountability of the national and Community statistical Authorities, after its revision, which was adopted on 28 September 2011 by the European Statistical System Committee. ■ Presidential Decree 226/2000 (Government Gazette No 195, Issue Α): “Organization of the General Secretariat of the Hellenic Statistical Authority”. ■ Articles 4, 8, 9, 10, 12 , 13, 14, 15 and 16 of the Law 2392/1996 (Government Gazette No 60, Issue Α): “Access of the General Secretariat of the Hellenic Statistical Authority to administrative sources and administrative files, Statistical Confidentiality Committee, settlement of matters concerning the conduct of censuses and statistical works, as well as of matters of the General Secretariat of the Hellenic Statistical Authority”. Labour Force Survey is harmonized with European legislation. The principal legal act is the Council Regulation (EC) No. 577/98 that stipulates the provisions on design, survey characteristics and decision making processes. Survey framework was modified in successive Commission regulations. (Regulation (EC) No 1372/2007 , Regulation (EC) No 2257/2003 , Regulation (EC) No 1991/2002).
Data sharing: A bilateral agreement is signed on the provision of anonymised EU LFS data to the National Statistical Institutes of other participating EU countries.

Policy: The issues concerning the observance of statistical confidentiality by the Hellenic Statistical Authority (ELSTAT) are arranged by articles 6, 7 and 8 of the Law 3832/2010, as amended by article 90 paragraph 8 of Law 3842/2010 and by article 10 of Law 3899/2010, as well as by article 8 of Law 2392/1996, which was brought back into force, in accordance with article 90 paragraph 8 of Law 3842/2010. Furthermore, ELSTAT disseminates the statistics in compliance with the statistical principles of the European Statistics Code of Practice and in particular with the principle of statistical confidentiality
Data treatment: − ELSTAT protects and does not disseminate data it has obtained or it has access to, which enable the direct or indirect identification of the statistical units that have provided them by the disclosure of individual information directly received for statistical purposes or indirectly supplied from administrative or other sources. ELSTAT takes all appropriate preventive measures so as to render impossible the identification of individual statistical units by technical or other means that might reasonably be used by a third party. Statistical data that could potentially enable the identification of the statistical unit are disseminated by ELSTAT if and only if: a) these data have been treated, as it is specifically set out in the Regulation on Statistical Obligations of the agencies of the Hellenic Statistical System (ELSS), in such a way that their dissemination does not prejudice statistical confidentiality or b) the statistical unit has given its consent, without any reservations, for the disclosure of data. − The confidential data that are transmitted by ELSS agencies to ELSTAT are used exclusively for statistical purposes and the only persons who have the right to have access to these data are the personnel engaged in this task and appointed by an act of the President of ELSTAT. − Issues referring to the observance of statistical confidentiality are examined by the Statistical Confidentiality Committee (SCC) operating in ELSTAT. The responsibilities of this Committee are to recommend on: • the level of detail at which statistical data can be disseminated, so as the identification, either directly or indirectly, of the surveyed statistical unit is not possible; • the anonymization criteria for the microdata provided to users; • the granting to researchers access to confidential data for scientific purposes. When data are disseminated in a form that would potentially allow direct or indirect identification of a person, (e.g micro data set), a certain set of rules is applied in order to prevent unauthorized disclosure: •Non-inclusion of the full name of individuals, the postal address of their dwelling and the Municipality where their dwelling is located. •Non-inclusion of the Department where the individuals’ dwelling is located. •Non-inclusion of the reference week of the quarterly survey data. •Inclusion of the Region (NUTS 2) where the individuals’ dwelling is located. •Inclusion of the degree of urbanisation of the Municipal/Local Community where the individuals’ dwelling is located, on the basis of : a) the most populated settlement, broken down into three (3) categories: urban, semi-urban and rural and b) the population density, broken down into three (3) categories: high; medium; and low density. • Inclusion of the extrapolation factor of households and individuals. • Inclusion of the age of individuals, with the exception of those aged over 85 years, who will appear under one category. • Inclusion of the citizenship of individuals, broken down into three (3) categories: Greek, EU Member States, Other countries. • Inclusion of the country of birth of individuals, broken down into three (3) groups: Greece, EU Member States and Other countries. • Inclusion of the family status of individuals, broken down into three (3) categories: a) single, b) married or in a civil partnership and c) widowed / divorced /separated. • Inclusion of the occupational status of individuals, broken down into three (3) categories: self-employed (with or without staff), salaried employees and assistants in the family business. • Inclusion of the number of employed persons of the local units in which the individuals work, broken down into the following size classes 1-10, 11-49, 50-249, 250 and over employees. • Inclusion of the occupation of individuals, by 2-digit ISCO code. • Inclusion of the branch of main economic activity of the enterprises in which the individuals work, by 2- digit NACE code. • Inclusion of the working hours of individuals, with the exception of individuals whose working hours exceed eighty (80) hours, who will appear under one category. • Information on wave will be suppressed in order to prevent users from tracking persons between successive sets of microdata. In specific cases, and after the approval of the confidentiality committee of ELSTAT, one or two of these rules can be relaxed.

Calendar: At the end of December of each year ELSTAT publishes a release calendar announcing the precise release dates for the next year. The calendar is distributed to the press and is available free of charge to all interested parties.
Calendar access: The calendar is disseminated on ELSTAT's website (http://www.statistics.gr) at the link: "Press Releases Calendar”.
User access: The data are released simultaneously to all interested parties through the Press Release entitled ''Labour Force'' which is made available to the media at 12:00. At the same time, the press release is distributed electronically to the subscribers. The press release is subsequently posted on the website of ELSTAT (http://www.statistics.gr). There is no internal government access to the data before their release to the public.

subset of Labour Force data is disseminated on a monthly basis. The complete survey results are disseminated on a quarterly basis, 90 days (at the most) after the end of the last reference week. Data are disseminated at 12.00 on the predefined date of the press release.

News release: • Labour Force Survey Monthly results • Labour Force Survey Quarterly results Published in ESLTAT website, path: Population and Social Conditions > Labour Market > Employment – Unemployment, http://www.statistics.gr/en/statistics/pop .
Publications: Labour Force estimations are included in the following editions, accesibe at ELSTAT’s website www.statistics.gr o The Greek Economy (fortnight edition, “e-publications” link) o Living Conditions in Greece (bimonthly edition, “e-publications” link) o Greece in Figures (quarterly edition, “e-publications” link) o Labour Foce Statistics (special edition for Thessaloniki International Fair, “in Greece” link)
On-line database: No exists
Micro-data access: Micro-data are available to users for free upon request to the Hellenic Statistical Authority, Statistical Information and Publications Division. Path: Products and Services>Statistical data request http://www.statistics.gr/en/statistical-data-request Confidentiality of the data is assured by the implementation of anonymization criteria (see 8.2).
Other: A number of tabulated data are available to users on the website http://www.statistics.gr/en/statistics/pop . Also, statistical data are provided to users by on-line application in ELSTAT, Statistical Information and Publications Division (see 11.4). Metadata – consultations Annual “User satisfaction survey” after having collected information from the User Satisfaction Questionnaire, filled by users to whom data was provided after a request, presents annual data on the number of users,in combination with other indicators, such as the response level to users’ requests, the kind of requested data,as well as the dissemination mode of statistical information. Path: Products and Services> User satisfaction survey, http://www.statistics.gr/en/user-satisfaction-survey

Documentation on methodology: The following scientific publications available only in the Greek language: • Ανασχεδιασμός του δείγματος της Έρευνας Εργατικού Δυναμικού από το έτος 1998 και εξής Ν. Πανταζίδης . • Αποτελεσματικότητα των εκτιμήσεων της Έρευνας Εργατικού Δυναμικού από το έτος 1998 και εξής Ν. Πανταζίδης Documents are available in pdf format (only in the Greek language), upon request Short methodological notes and survey questionnaires are available at ELSTAT website, path Population and Social Conditions > Labour Market > Employment – Unemployment, http://www.statistics.gr/en/statistics/pop .
Quality documentation: A “User oriented quality report” is available at ELSTAT website http://www.statistics.gr/en/statistics/- /publication/SJO01/2016-Q4.

Assurance: Labour Force Survey complies with Eurostat standards concerning the selection and the size of the sample, the design of questionnaires, the survey’s frequency and the information collected. Collected questionnaires are checked for completeness and quality of information. The final data base is checked for data validity by ELSTAT and Eurostat. Regarding the data collection method, the use of electronic questionnaires on laptop computers is steadily expanding, thus helping to significantly accelerate the production of research results. Under consideration is also the use of a call center for repeated household interviews, a change in data collection, which will also improve the timely production of survey results and interview quality.
Assessment: Labour Force Survey is considered a reliable source of information with a methodology that meets high standards. Nevertheless, Labour Force Survey is a sample survey and as a result, the results are accompanied by sampling errors. Basic quality indicators or Labour Force Survey, (sampling errors, response rates) are computed quarterly and annually and included in a standard quality report submitted to Eurostat.

User needs: The main users of the Labour Force Survey data are international organizations (European Commission, OECD, European Central Bank, Unesco, IMF, etc) and a large number of national authorities and institutions (Ministries, Banks, Universities, Institutes) but also the press, researchers and the general public. The main indicators produced by the Labour Force Survey describe the evolution in main labour market (changes in the level of employment, unemployment), provide information on the allocation of working population in different sectors of economy and on the characteristics of labour force (age, educational level, participation in education, etc.)
User satisfaction: ELSTAT does not carry out a user satisfaction survey specifically for the users of the Labour Force Survey. However, there is continuous communication with the main users of survey results and their opinion and remarks are taken in to account in the development of Labour Force Survey and the production and dissemination of its results.
Completeness: Labour Force Survey collects information on all variables that are included in the relevant Council Regulations and additionally on a small set of characteristics that are surveyed only at national level.

Overall accuracy: The size of the Labour Force Survey sample allows for the production of estimates with high accuracy at t country level and at the most of NUTS 2 areas of Greece.
Coverage error: Refers to deviations between sampling frame and target population (see 4.6). The sampling frame is based on the current census results. The primary sampling units consist of a number of building blocks.. The design and selection of the primary sampling units is based on the number of private households residing permanently in these areas at current census. The secondary sampling units (that is households and dwellings) are selected after the selection of the primary sampling unit and after the compilation of a compete list of the private household dwellings in the PSU. The list is updated every 6 quarters (when a new systematic sample of dwellings is selected in the primary sampling unit). The main issues pertaining to the frame quality are: • The more the time interval elapsed since the census, the less accurately the probabilities of selection reflect the “real size” of the selected primary sampling units. • Sample size can be different, and even significantly different from the expected size, due to considerable changes in the “size” (that is, the number of household dwellings) of a PSU. • It is difficult to control the way listings are updated. Over-coverage and under-coverage can be both present. Undercoverage (the percentage of persons that are not covered by the sampling frame) is estimated at about 1%. These are mainly persons residing in collective households and persons residing in houses outside builded areas.
Measurement error: Measurement errors are distinguished into: a) response errors, i.e. when respondents provide untrue or incorrect information, caused, among others, by the following : • Sensitive questions (like the existence of a second job, income, receiving unemployment allowances, etc) • Proxy answering, mostly for questions about the motives or wishes of a person • Repeated interviewing of the same household for 6 consecutive waves imposes a serious burden on the interviewed households • Cases invlolving false data registration due to responses. For example, it may be the case of incorrect or incomplete description of the occupation, incorrect number of hours worked during the reference week, false salary etc. ,and b) interview errors, i.e. all cases of false data registration caused by mistakes made by the interviewer . For example, the interviewer may formulate a question incorrectly, ask questions in the wrong order, or incompletely record open-ended answers (eg. profession description).
Non response error: Non response errors are due to non-contacts (failure to come into contact with the household) or to the refusal of the household to provide information. Non-response error rate for 2015 LFS were as follows: Quarter Non response rate (%) Refusals (%) Non contacts (%) Other reasons (%) 1 25.6 7.6 7.4 10.6 2 25.6 7.6 7.3 10.7 3 25.0 8.0 7.2 9.8 4 25.4 8.3 7.3 9.8 Yearly 25.5 8.0 7.3 10.2 NUTS-2 area Yearly non-response rate (%) EL30 Attiki 38.3 EL41 Voreio Aigaio 22.1 EL42 Notio Aigaio 37.4 EL43 Kriti 21.1 EL51 Anatoliki Makedonia, Thraki 13.0 EL52 Kentriki Makedonia 21.4 EL53 Dytiki Makedonia 27.5 EL54 Ipeiros 20.7 EL61 Thessalia 25.9 EL62 Ionia Nisia 36.6 EL63 Dytiki Ellada 26.4 EL64 Sterea Ellada 16.7 EL65 Peloponnisos 9.7 Unit non response is adjusted at primary unit level (design weights are multiplied by the factor a = eligible household in sample/househols interviewed). Nevertheless, it is not clear whether this adjustment "removes" the whole bias attributed to non-response.
Processing error: The number of records with errors is about 12% (with a mean number of 3 errors per record). There is no information on the source of these errors (that is, codification, data capture or editing). These errors are eventually corrected after the application logic controls.
Model assumption error: No models for estimation of non-sampling errors are applied.

Timeliness: Survey results are available 90 days after the end of the reference period
Punctuality: There were no delays in the publication of results during 2015

Geographical: The definitions of the variables used in the Greek Labour Force Survey are fully in line with Eurostat Regulations
Over time: Consistency of time series and comparability of the estimates over time are affected by changes in key parameters of the survey as sample design, population estimates, the questionnaire, definitions of characteristics surveyed and classification systems. Most noticeable changes concern the following: • Until 1997, the Labour Force Survey had been producing estimates on a yearly basis (spring quarter). From 1998 onwards the Labour Force Survey is a continuous quarterly survey. • Total sample replacement was made in 1983, 1993, 1998 and 2004. Also, the sample was gradually replaced during the 2009-2010 period as well as from the 2nd quarter of 2015 to the 3rd quarter of 2016. • In 2004, the method of substitutions, for dealing with non-response was discontinued. • Derivation of survey results: o From 1981 to 1997 the survey estimations were derived by applying a reducing factor equal to the product of the inverse of the sampling fraction for a population adjustment factor, uniform for the whole country. From 1998 the reducing factor is based on the estimated population distribution by sex and age groups in every NUTS-2 level. o Since 2004 a correction factor adjusting for non-response is applied. o The population adjustment factors are calculated using the current population estimates, which in turn are based on the results of the latest census. • Changes in the survey questionnaire occur almost every year with major changes in 1992, 1998 and 2006. Changes of a lesser extent occurred in 1983, 1987, 1999, and 2003. Most important changes were: 1999: - Introduction of variables that describe relationships between household members. - Introduction of separate questions on “search-job” activities - Introduction of questions on employees salary 2003: Introduction of questions on field of studies 2011: Introduction of questions for job-related education 2006: Codification of sector of economic activity at 3 -digit level • Changes in codification: o 2006: Codification of NACE in 3-digit level o 2008: Introduction of NACE Rev2 for the codification of economic sector (see 4.2) o 2011: Introduction of ISCO-08 for the codification of occupation (see 4.2)

Internal: The LFS estimates have full internal coherence, as they are all based on the same set of microdata and they are calculated using the same estimation methods
Sub annual and annual statistics: Coherence of LFS data with registered unemployment: There are differences between these estimates due to differences both in measurement and definitions. LFS is using the ILO concept of unemployment while Unemployment register includes a person if he has contacted the unemployment office and declared him of herself as unemployed. As a consequence, persons with "small" jobs or part-timers, can be included in registered unemployment. At the same time, it is not always the case that someone who is LFS unemployed is registered at the unemployment office. There are relatively small differences (register unemployment is higher) but both estimates show same trends at country level. The total number of ILO unemployed for the 4th quarter of 2016 is 1,123,989 while the mean number of registered unemployed is 915,150. If we take in to account the registration in Public Employment Offices (as reported in LFS) the difference is much smaller: according to LFS, 848,981 "ILO - unemployed" are registered in employment office.
National Accounts: Coherence of LFS data with National Accounts: There are differences between the two estimates that are due to different definitions, concepts and coverage. National Accounts cover all population while LFS covers only population living in private households. National Accounts use LFS as the main source of data on employment but in certain cases, Business Surveys are also used. The National Accounts estimation for the number of persons in employment is slightly higher than the LFS estimation.

Persons working for Labour Force Survey Number of staff involved in central and regional offices, excluding interviewers (Full-time equivalents) Total 26 - of which professional and managerial 2 Number of surveyed households Total Households surveyed for the first time Households surveyed for the 2nd, 3rd, ..6th time Surveyd households in 2016 109,800 17,900 91,900 Surveyd persons in 2016 249,730 40,775 208,955 Total cost for data collection (by not permanent staff of ELSTAT): 534,649 euros

Policy: Survey estimates are based on the latest census data. When the latest census data are available, data weights are revised to reflect the new information on population totals.
Practice: Data weights are revised for the 4 years before the census and for the years between the census and the first year when the latest census results are available. In June 2004 the results of the period from 1998 to 2003 were revised in accordance with the results of the 2001 census. In June 2014 the results of the period from 2001-2013 were revised in accordance with the results of the 2011 census. Initially, results for the period from 1998 to 2003 were based on the 1991 census, whereas results for the period from 2004 to 2013 were based on the 2001 census.

Source data: Labour force survey is a sample survey covering the population living in private households. The selection of households to be surveyed follows a two stage stratified sampling scheme. Total country is stratified in 206 strata. These strata are formed by allocating municipalities and communes of every NUTS 3 in three different groups (Agglomerations and Municipalities with 10.000 inhabitants or more, Municipalities and Communes with 2.000 to 9.999 inhabitants, and Communes up to 1.999 inhabitants). The exceptions are Athens and Thessaloniki agglomerations, which are divided into 31 and 9 strata, respectively. From the second quarter of 2015, the sampling frame was undergoing a total renewal process that was completed in the third quarter of 2016 (ie, the rate of renewal was 1/6 per quarter). The final sample, after full renewal, now consists of 2820 surface units. In particular: • In the period between the 2nd quarter of 2015 and the 2nd quarter of 2016, some of the surface units (housing units) are selected with a probability proportional to the number of households residing in them at the 2001 census) and the remaining ones with probability proportional with the number of households staying in them at the 2011 census) • From the 3rd quarter of 2016, all surface units were selected with a probability proportional to their size at the 2011 inventory and based on the revised sampling frames. At the second sampling stage a systematic sample of dwellings is selected in every primary sampling unit. All households residing in selected dwellings are asked to participate in the survey. All the individuals who are members of the selected households are interviewed. Total sample size is about 25,000 households per quarter.
Frequency of data collection: Data are collected throughout the year. The year is divided in 4 quarters: 1st (January, February, March), 2nd (April, May, June), 3rd (July, August, September) and 4th (October, November, December). The quarterly sample is distributed uniformly in the 13 (or 14) weeks of the quarter.
Data collection: The Labour force survey sample follows for a “rotational” pattern. Every quarter, the 5/6 of the sample remains the same, while the 1/6 is “rotated” - that is new households are interviewed. New households are interviewed by personal, face-to-face, interviews. Subsequent interviews of the same household (during the following quarters) can be carried out either by face-to-face interviews either by telephone.. Almost 10% of the first wave interviews is conducted by the use of a laptop (CAPI). For the following cases a paper questionnaire is used.
Data validation: Data are validated through a series of checks which detect inconsistencies between dates reported by interviewed persons, between educational attainment and profession, profession and sector of economic activities, inconsistencies between answers given to different part of the questionnaire and inconsistencies in the reported structure of the households. When detected, these problems are resolved either by recontacting households or, when possible, using previous data for the same household.
Data compilation: The Labour Force Survey results are produced by weighting sample data. Data weights are computed in a 3 – step procedure. In the first step, a design weight is assigned to each person in the data file. This weight is determined by the estimated probability of selection of the particular household where the person lives . In the second step, a non response correction factor is computed, at primary unit level: Non response correction = number of eligible households in primary sampling unit/number of households .that responded. At the third step, data are post stratified: Totals are computed for 208 post – stratification cells, which are defined by 13 NUTS 2 areas x 8 age groups x sex. These totals are estimated by weighting sample data (individuals) by design weights and non response correction factor. Finaly, post stratification correction factors are computed for each individual so that estimations from Labour Force Survey are consistent with estimated population totals for post - stratification cells. These estimations are based on latest census results, births, deaths and known migration.
Adjustment: The LFS quarterly results are not adjusted
Imputation-rate: No imputation is performed in the LFS data.
Seasonal adjustment: Characteristics studied by LFS (number of employed, unemployed persons etc) are subject to strong seasonal variations: for example, in Greece, employment increases in summer due to tourism (although there are countervailing factors). Therefore, seasonal adjustment is applied in monthly estimates since 2004 and for time series of employment and unemployment by sex, age groups and Decentralized Administration. Seasonally adjusted series are produced by means of TRAMO&SEATS algorithm. It should be noted that due to seasonal adjustment the whole series with monthly estimates is recalculated every time a new month is added in time series. As a result, estimations for the previous months are often revised.