Labour Force Survey, from 2021

Statistical Office of the Republic of Serbia (SORS)

Labour Market Statistics Department, Labour force survey group 

Belgrade, 5 Milana Rakića St.

ars@stat.gov.rs

Labour Force Survey (LFS) is a research focused on the household and is designed to obtain information about the labour market and labour force characteristics.

Regarding methodology, organization, sampling procedure, questionnaire design and definitions of employment and unemployment, LFS is carried out in line with the standards and recommendations of the International Labour Organisation – ILO as well as with Eurostat regulations, which allows comparing a large number of LFS data with equivalent data from other countries, particularly European.

The main objective of this Survey is to obtain data on three main mutually exclusive population contingents – employed, unemployed and persons out of labour force.

As for the employed, LFS registers their professional status, the form of ownership in which they work, the rights they exercise at the workplace, occupation and activity, number of working hours, additional work (if any), etc. In the case of the unemployed, LFS examines the way they look for a job, the length of the job search, previous work experience, etc. For persons outside the labour force, collected data refer to the reasons for not looking for a job as well as to their attitude towards the labour market (potential labour force).

Apart from the previously mentioned categories, demographic, socio-economic, educational and other characteristics (age, sex, marital status, education, citizenship, national affiliation, health, etc.) are also studied.

The results of the Survey are published as aggregates, thus securing full confidentiality of information about households and individuals, according to the provisions of the Law on Official Statistics.

Survey data are published on quarterly and annual basis.

The following international classifications are used in Labour Force Survey:

• International Standard Classification of Occupations (ISCO – 08);
• Statistical classification of economic activities (NACE, rev.2), which is comparable to UN classification of activities ISIC – rev.4;
• International Standard Classification of Education, ISCED–2011;
• International Classification of Status in Employment (ICSE – 93).

Labour Force Survey covers all sections defined by NACE rev. 2.

The population is classified as employed, unemployed and out of labour force based on the information from the questionnaire concerning the activity of the respondents in the reference week. Data obtained in this way differ from the data on employed and unemployed persons obtained through other statistical researches.

The Survey does not take into account the formal status of the respondent, but her/his employment status is determined based on the activity that is carried out in the reference week. Thus, in addition to the persons who have a formal job, employed persons in this Survey can also be individuals who have no formal employment, but they have performed some work (at least one hour) during the reference week in order to earn their living.

Similarly, persons out of labour force are formally unemployed persons (as they are noted in the National Employment Service) if during the four weeks preceding the survey have not undertaken active steps to look for work and was not able to start working within two weeks of the survey. In the second case, formally unemployed or persons out of labour force (persons without a formal job, retired, student, housewife, etc.) that have performed in the reference week any paid work shall be considered employed, regardless of their formal status.

Employed persons comprise persons aged 15 to 89 who, during the reference week, were in one of the following categories:

• Persons who during the reference week worked for at least one hour for pay or profit, including contributing family workers.
• Persons with a job or business who were temporarily not at work during the reference week but had an attachment to their job. The following groups have a job attachment:
  • Persons not at work due to holidays, working time arrangements, sick leave, maternity or paternity leave; persons in job-related training;
  • Persons on parental leave, either receiving and/or being entitled for job-related income or benefits, or whose expected duration of the parental leave is 3 months or less;
  • Seasonal workers during the off-season, where they continue to regularly perform tasks and duties for the job or business, excluding fulfilment of legal or administrative obligations;
  • Persons temporarily not at work for other reasons where the expected duration of the absence is 3 months or less.

• Persons producing agricultural goods whose main part is intended for sale or barter.

Persons in own-use production work, voluntary workers, unpaid trainees and persons involved in other forms of work as defined in the 19th International Conference of Labour Statisticians (ICLS) Resolution concerning statistics of work, employment and labour underutilization, adopted on 11 of October 2013, are not included in employment on the basis of those activities.

Employment rate is the percentage share of employed population in the total population of the same age group.

Formal employment includes:

• Persons who have a formal contract on employment, i.e. an employee-employer relationship for a definite or indefinite time,
• Persons who perform independently an activity in registered ownership or are founders of registered enterprises or entrepreneur’s shops,
• Persons who undertake an agricultural activity registered in official government institutions.

Informal employment involves:

• work in non-registered enterprises,
• work in registered enterprises, but without a formal contract of employment.
• work of contributing family workers.       

The informal employment rate represents the share of informally employed in total employment.

Unemployed persons comprise persons aged 15 to 74 who were:

• during the reference week not employed according to the definition of employment described in paragraph 1; and
• currently available for work, i.e. were available for paid employment or self-employment before the end of the two weeks following the reference week; and
• actively seeking work, i.e. had either carried out activities in the four week period ending with the reference week to seek paid employment or self-employment or found a job to start within a period of at most three months from the end of the reference week.

Seasonal workers not at work during the reference week (off-season) but who expect to return to their seasonal job are to be considered as "found a job".

The unemployment rate represents the percentage of the unemployed in the total number of active population of the same age group.

The long-term unemployment rate represents the share of the unemployed for more than a year in the labor force (employed and unemployed).

The NEET rate represents the share of persons aged 15-24 (or 15-29) who are not employed, not in education, or in training in the total population of that same age group.

Active population – labour force includes all employed and unemployed persons.

Potential active population includes persons who take active steps to find a job but cannot start working immediately, i.e. within two weeks, as well as persons who can immediately start working but did not take active steps to find a job.

This contingent includes so-called discouraged persons, i.e. persons who do not undertake steps to find a job because they are convinced they cannot find one although they could start working immediately in the case a job was offered.

Activity rate is the percentage share of active population in the total population of the same age.

Persons outside the labour force comprise persons who were in one of the following categories:

(a) Persons aged below 15;

(b) Persons aged above 89;

(c) Persons aged 15 to 89 who were, during the reference week, neither employed nor unemployed according to the definitions of employment and unemployment.

The outside the labor force rate is the percentage of the population outside the labour force in the total population of the same age group.

The household selected in the sample is the unit of selection and the unit of observation in the Survey is the household selected in the sample, and each member of the selected household is the unit of survey.

Basic socio-demographic data are collected for all persons in selected households, and work activity data are collected for persons aged between 15 and 89 years.

In the Labour Force Survey, the target population consists of all persons living in private households. The target population is determined based on usual residence. "Usual residence" is the place where a person usually spends a daily rest period, regardless of temporary absence for recreation, vacation, visits to friends and relatives, work, medical treatment or religious pilgrimage. The "usual inhabitants" of a particular geographical area are :

• Persons who have lived in their usual residence continuously for at least 12 months before the observed week; or;
• Persons who came to their usual residence in the previous 12 months before the observed week with the intention to stay in it for at least one year.

Where the circumstances described in point (1) or (2) cannot be established, "usual residence" may be the place of legal or registered residence.

The usual residence for all persons in the target population is determined based on the "most of the time" criterion, i.e. the person is registered in the place of residence where she/he spends most of the year (more than 6 months). This means that if a person lives in more than one place, the place where she/he spends most of the year is considered her/his usual residence. This applies to people who have more than one home, to children who alternately live in two places, or to people who live outside their main household for a long time due to work.

The cases to which the "most of the time" criterion applies are:

1. For primary and secondary school students and persons who work outside the place where the main household lives during the week, but return to it on weekends, the usual residence is the place where the main household lives;
2. For students, their temporary address is treated as their usual residence if it is a private address.
3. For children who alternately live in two places and spend equal time with both parents / guardians, the place where the child is at the time of the survey is taken to be the usual place of residence. This usual residence should be the same in the first and subsequent waves of surveys.

In special cases, the following rules apply:

1. For persons living outside the main household for a longer period of time due to work, either in the territory of the Republic of Serbia or abroad, the place of residence of the main household can be considered as their usual residence. Provided that they significantly contribute to the budget of the main household, and do not have another household in which they live.
2. For persons studying outside the place of residence of the main household, either on the territory of the Republic of Serbia or abroad, the place of residence of the main household can be considered as their usual residence if students are economically dependent on the main household and do not have another household in which they live.
3. For children who live alternately in two places and spend the same time with both parents / guardians, the usual residence can be with the parent / guardian who receives child benefits, or with the parent / guardian who contributes the most to the child's maintenance.

The target population are not persons who stay or intend to stay in the Republic of Serbia for less than a year. Nor are persons who are absent or intend to be absent from the surveyed household for a year or longer (live and / or work abroad or elsewhere where they have a second household, they have permanently moved out of the household, etc.).

Reference territory is the territory of the Republic of Serbia without the region of Kosovo and Metohija. Since 1999, SORS has no available data for AP Kosovo and Metohija, therefore they are not included in the data for the Republic of Serbia (total).

LFS was first carried out in 1994 in our country as a pilot survey. From 1995 till 2008 it was conducted regularly once a year, then over the period 2008 – 2013 the survey was carried out twice a year (in April and October). In 2014 it was carried out four times (quarterly – in February, May, August and November) and in 2015, it switched to a continuous periodicity which is still applied.

Not applicable.

Most results are expressed as a number of persons (thousands) or as rates (employment rate, unemployment rate or growth rate). There are also variables that are reported in other units of measurements (age in number of years, working hours in hours, etc.).

The LFS is conducted as a continuous survey, which means that each week during the year is a reference week. The reference week is the week preceding the survey and covers the entire calendar week (Monday to Sunday).

The status of the labor force is determined in relation to the reference week, so that week is also called the observed one. The first reference week of the year must include the first Thursday of the year, and the every quarter includes 13 referent weeks.

The power and responsibilities for collecting, processing and publishing statistical data to the Statistical Office of the Republic of Serbia (SORS) are given and regulated by the Law on Official Statistics (“Official Journal of the RS”, number 104/09).

Starting from 2021, the Labour Force Survey 1 is conducted as laid down in Regulation (EU) 2019/1700 of the European Parliament and Council from 10 October 2019. The Regulation establishes a common framework for European statistics on persons and households based on the data on individuals collected on the basis of a sample, which amends Regulations (EC) No 808/2004, (EC) No 452/2008 and (EC) No Regulation (EC) No 1338/2008 of the European Parliament and Council and repeal Regulation (EC) No 1177/2003 of the European Parliament and Council and Council Regulation (EC) No 577/98, and in particular Article 7 (1), Article 8 (3) and Article 13 (6) thereof.

Not applicable.

Data confidentiality is regulated by:

• Law on Official Statistics ("Official Gazette of RS", No. 104/2009), Articles 44, 45, 46, 47, 48, 49.
• Rulebook on protection of statistical data in the Statistical Office of the Republic of Serbia
• Instructions on data and information protection measures in the Statistical Office of the Republic of Serbia

Documents are available in annex.

Confidential data is treated in accordance with the prescribed principles of confidentiality. See Law on Official Statistics, link in annex.

The publication calendar is available on the SORS website on December 1 of the current year for the entire following year - link in annex.

The daily time of publication for all editions of the SORS is 12 o'clock (noon).

Deviations from the set dates are announced in advance and explained in the Calendar.

The release calendar is available on the SORS Website. Link in anex.

In line with the Law on Official Statistics (“Official Gazette of RS“, No 104/2009) and European Statistical Code of Practice, all users are treated equally. LFS data are published on the SORS Website, following which those data are simultaneously availabe to all users. Any deviation from the date set in the release calendar must be announced and explained.

Data is published quarterly and annually.

LFS data are published quarterly in press releases.

The Statistical Office of the Republic of Serbia publishes the following publications:

• Statistical release “Labour Force Survey” – quarterly data;
• Bulletin “Labour Force Survey in the Republic of Serbia” – annual data;
• Data from the Labour Force Survey are also available in the publications “Statistical Yearbook” and “Statistical Pocket-book“.

The publications can be accessed through the link given in annex.

Database

Мicrodata are available upon users‘ request according to the criteria laid down in the Law on Official Statistics and rules defined in the Rulebook on the method and procedure of transmission of data produced by the SORS.

Statistical micro-databases that are released for use for scientific research purposes contain reduced information about the respondents in order to prevent identification of the surveyed individuals or households. In addition to the fact that publicly available databases do not contain information on the name, surname and address of individuals, additional personal data protection measures apply:

• the age of the respondents is given in five-year groups;
• employees’ earnings are given at intervals of 10 groups;
• the country code (birth, citizenship, work) is given separately for Serbia and the countries of the region (Bosnia and Herzegovina, Croatia, Montenegro, North Macedonia), while the other countries are grouped into three sections: EU countries except Croatia, other European countries, rest of the world;
• occupation is given at the 3-digit level
• activity is given at the sector level (21 groups in total);
• the household identifier changes at each subsequent annual basis to prevent monitoring of household members over time.

The above data groupings are made in accordance with the rules applied by the European Statistical Office - Eurostat aiming to personal data protection. More information can be found at the link in the annex.

Data that require additional processing are to be delivered to Dissemination Unit, after which they are to be forwarded to the LFS group that begins the process of production/processing of requested data. Afterwards, the requested data are delivered to users.

The complete LFS methodology, both the old and new one, being used since 2021 is available on the SORS Website in the scope of Referent Metadata. Link in annex.

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SORS is working on improving the quality of the Labour Force Survey by adopting the following EU regulations:

• Regulations (EU) 2019/1700 of the European Parliament and Council of October 10, 2019 establishing the common framework for European Statistics on individuals and households based on data on individuals collected on the basis of a sample, which amends Regulations (EC) No 808/2004 and (EC) No 452/2008 and (EC) No 1338/2008 of the European Parliament and Council and repeal Regulation (EC) No 1177/2003 of the European Parliament and Council and Council Regulation (EC) No 577/98, and in particular Article 7 (1), Arcile 8 (3) and Article 13 (6) thereof.

Since 2010, SORS transmit annual and quarterly LFS quality reports to Eurostat.

Special attention is paid to harmonizing the main quality indicators and main LFS concepts, such as:

• ILO concept of employment and unemployment,
• sampling design and sampling errors,
• weighting schemes,
• non-response,
• interviewers and fieldwork organisation,
• survey modes,
• information for users,
• coherence and cross-country comparability.

In addition to improving the methodology, constant control of the obtained results and the interviewers is carried out, as well as the improvement of the instruments for conducting the survey.

The Labour Force Survey can be considered as a reliable source of data, knowing that Eurostat and ILO standards and definitions have been applied in questionnaire design and methodology development.

The Survey is sample-based and is therefore subject to sampling errors. Depending on sample size, figures with a few observations are marked in LFS publications and warning about unreliability of the figures is given for them.

The Labour Force Survey is carried out in every European country as well as in many other countries around the world following common concepts and guidelines. This makes the Labour Force Survey the most adequate Serbian survey for international comparisons on labour market statistics.

The Labour Force Survey is used for monitoring the labour market.

The data that are most frequently asked for but are not available from other sources are those on:

• unemployment;
• formal/informal employment (undeclared work);
• characteristics of the main and additional job, such as hours of work, overtime, absence from work, reasons for absence from work, methods for seeking employment, reasons for not seeking employment, reasons for work on permanent or temporary base, reasons for part-time work, etc.

LFS data are used by national and international users.

National users are the Government organisations of the Republic of Serbia such as: the Ministry of Labour and Social Affairs, Ministry of Science and Technology, Ministry of Youth and Sports, National Bank, National Employment Service, local authorities, etc. Other national users are various academic and research institutions (universities and institutes), enterprises, journalists and individual users such as students, scientists, researchers and others.

The National Accounts use LFS data to produce the adequate estimations of the labour input. For this purpose, the variables used are: actual hours of work, section of activity, professional status, type of labour contract etc.

The international users are: Eurostat (for main LFS indicators), UNESCO and UNICEF (for educational data), ILO (for employment and unemployment), World Bank, International Monetary Fund (IMF) and others. Some countries from the region need LFS data for various regional projects.

Every two years, a Survey on User Satisfaction is conducted via a web survey.

The results of the survey are available on the SORS Website. Link in annex.

LFS complies with Regulation (EU) 2019/1700 of the European Parliament and Council, making the data complete.

The LFS is the most reliable source of data when comparing labour market internationally. Constant harmonization with international recommendations and standards make the Labour Force Survey a reliable research. As with any sample-based survey, this survey has sampling errors which are associated with sample selection and non-response patterns.

Sampling errors are a measure of the variability between the estimates from all possible samples. The extent of variability is not known exactly, but can be estimated statistically from the survey data.

In the dissemination phase, it is not possible to publish each estimate with its sampling error. In order to allow users to use sampling errors (for selected data) when doing analyses, approximate values of sampling errors  have been calculated based on regression model.

Tables with approximate values of sampling errors for totals and means, method of using said tables and calculation of the CVs for rates and changes are available in the Methodology for Users – “Labour Force Survey, 2017 (pages 25-26). Link of the publication is given in the annex.

а) Coverage errors

Demolished dwellings, evicted households and changed purpose of the apartment are the main causes of over-coverage. Under-coverage problems result from non-updated enumeration areas.

Errors related to coverage (over-coverage, under-coverage, as well as wrong classification) are documented in the Quality Report of the Labour Force Survey.

b) Measurement errors

No measurement error estimates are available.

c) Processing errors

Data can be modified and edited in the course of the survey/interview. If an interviewer wants to modify the initial respondent’s answer when she/he sees there has been an error, she/he can do it on site. Upon the arrival of data in the head office, additional control is to be done, as well as the coding of occupations, economic activities and fields of education. Editing and processing phases refer to detecting logically incompatible information, as well as to their modification. Logical control in data entry is incorporated in the application, thus disabling the interviewer to enter illogical data and as such limiting such cases to the minimum.

There are no available estimates on the number of processing errors in the LFS.

d) Non-response errors

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Annual data are published once a year, more specifically at the last working day of March. The quarterly data are published four times a year (I quarter of the year – May of the same year, II quarter of the year – August of the same year, III quarter of the year – November of the same year and IV quarter of the year – February of the following year). The data are published approximately 6 to 7 weeks after the end of the fieldwork or more specifically on the last working day of the following month.

All data are published according to the release calendar.

The data are comparable on the level of regions and districts with exception of the region Kosovo and Metohija for which data are not collected. The data are also comparable with other countries of the Balkans and EU.

All definitions and procedures are laid down by the European Union, which makes the Survey suitable for both overall and very specific international comparisons of labour market issues.

The LFS was first introduced and carried out in 1994 as a pilot survey. From 1995 till 2007 it was conducted regularly once a year, in October. In 2004, the questionnaire was harmonised with the EU Regulation No. 577/98 when data series were interrupted for the first time. Over 2008 – 2013, the survey was carried out twice a year (in April and October). In 2008, it was additionally aligned with the EU Regulation No. 377/2008. Supplementary questions covering the contingent of employed persons were introduced as well as variables concerning education; this harmonisation led to a second break in data series. In 2013, the sampling frame was changed (2011 Census), causing the next break in data series. In 2014, the survey was carried out four times a year (once in every quarter – in February, May, August and November). Then in 2015, it switched to a continuous periodicity. During this period modifications were made not only to methodology and periodicity but also to sample size.

Due to the change in the rating system in 2015 (post stratification according to NUTS-3, gender and five-year age categories), the first revision for data from 2014 was made. Due to the introduction of uniform weights at the level of individuals and households in 2016, a revision of the data for 2014 was redone (rev.2), as well as a revision of the data for 2015.

Starting from January 2021, LFS is conducted based on and according to the new Regulation of the European Parliament and Council. The new European regulation requires from EU countries to apply the new redesigned concepts in LFS since 2021. The objective of the revised methodology is to improve the content of the survey in order to monitor with more precision labour market trends, having in mind constant changes in its dynamics and structure. The new standardized questionnaire ensures better overall data quality and international comparability.

Even though LFS has been conducted without interruption since 1994, all the mentioned changes have led to reduced data comparability between periods. Consequently, data collected from 2004 to 2007 are mutually comparable, as well as those from 2008 to 2013. Owing to performed revisions, data from 2014 to 2020 are also mutually comparable. However, since 2021, due to changes in main concepts in LFS the comparability with previous years has been lost. Even though improvements over time have led to time series break, comparability between the main LFS indicators (number of employed persons, unemployed persons and inactive persons) for the period from 2008 is still high.

1. Coherence of the Labour Force Survey with Population Statistics

Population statistics are not fully comparable with socio-demographic data collected by the Labour Force Survey. There are many conceptual differences between them, for example:

• Labour Force Survey includes private households while population statistics cover the entire population.
• Population statistics refer to specific dates (year) whereas the Labour Force Survey is conducted continuously and each week is a reference week.

2. Coherence of the Labour Force Survey with National Accounts

The LFS includes all employed persons being residents (permanent citizens) of the Republic of Serbia (national concept), particularly the persons working on the territory of the country. National accounts applies the so-called “domestic concept” that includes all employed persons, whether residents or not, who belong to the production activity performed in the country. This implies that National Accounts cover overall employment in agriculture and overall employment not being monitored by the official economy. 

National accounts estimate the number of employed persons based on different sources, such as:

• official statistics on the number of formal employment,
• structure of formal and informal employment from the LFS,
• data on employees from financial and tax sources.

In the Republic of Serbia, National Accounts currently estimate only experimentally the number of employed, so the procedure of estimation of employed has not been published yet.

3. Coherence of the Labour Force Survey with Business Statistics

Data on registered employment differ from data from the Labour Force Survey for reasons cited below:

• The collection method is different. Survey data are collected from household members selected in the sample, while those on registered employment are derived from the database Central register of compulsory social insurance (CRCSI);
• The data source used in the Survey is respondents’ responses given to interviewers, while that for registered employment is the database CRCSI;
• The Unit of observation in the Survey is every member in the randomly selected household, while that for registered employment is the contribution payer and insurants;
• The period of observation of the activity of a person in the Survey is the week preceding the survey, while the second to last working day in the month is taken to be the period of observation for registered employment;
• Definitions of employment are not the same. Data on the number of employed persons from administrative sources include only formally employed persons (i.e. the persons who are registered in CRCSI and who are insured based on employment, running own business and performing agricultural activities), while the Labour Force Survey (by the international ILO definition) evaluate both formal and informal employed persons selected in the sample (randomly selected part of population).          
• Apart from different definitions, these two surveys have also different periodicity. The frequency of collecting data on employed persons that are derived from administrative sources is monthly, while in the Labour Force Survey data have been gathered continuously since 2015, and are published on quarterly basis.

4. Coherence of the Labour Force Survey with the National Employment Service

There is a difference between the definition of unemployed persons in the LFS and registered unemployment:

• LFS – According to ILO definition unemployed persons are all persons aged 15-74, who did not have a paid job in the reference week, actively sought work in the previous four weeks and can start work within two weeks after the reference week or do not seek employment because they have already found a job on which they will start working within 3 months.
• Registered unemployment - Unemployed persons are all persons aged 15-65 who are registered with the National Employment Service, do not have formal employment, are immediately available to start working in case of a job vacancy and are actively seeking work. 

LFS estimates for a given reference period have full internal coherence, as they are all based on the same corpus of microdata and they are calculated using the same estimation methods.

Annual data are calculated as the average of quarterly data, which ensures coherence.

The general revision policy of the Statistical Office of the Republic of Serbia represents a global framework allowing that every statistical domain defines its own revision policy in accordance with its specific features. 

 The general SORS revision policy establishes:

• general rules of revision of published data, 
• forms of information of users as to possible revision causes, 
• categorization of revisions, and
• documentation covering all revision aspects.

The general revision policy is available on the link in annex.

1. Starting from 2021, the Statistical Office of the Republic of Serbia (SORS) has switched to a new methodology of the Labour Force Survey (LFS), in accordance with the regulation of the European Parliament. In order to ensure the comparability of data after changes in the methodology, a revision of the LFS time series for the period from 2010 to 2020 was preformed.

In accordance with the Eurostat  recommendations for correcting breaks in time series , for the revision purposes, in 2020 a parallel pilot survey (according to the new methodology, valid from 2021) and a regular survey (according to the old methodology, valid until 2020) were conducted. By comparing the results of the regular and pilot survey, correction factors were obtained for the estimate of the break, caused by changes in methodology.

Methodological approach used to calculate the correction factors implies two estimates of the same variable available according to the old and new methodology for several points in time, based on which correction factors are determined as the quotient or difference of value estimate according to the new and old methodology. As the correction factors calculated at different time points  may be different, correction factors obtained by comparing the results in the fourth quarter of 2020 were used to correct the break, as the most reliable ones. The revision of the LFS time series for the period from 2010 to 2020 was performed by applying these correction factors in the following way:

• If the correction factor is calculated as the quotient of value estimates according to the new and old methodology, it is applied as a multiplicative factor, meaning that the revision is performed so that each value in the time series is multiplied by that factor.
• If  the correction factor is calculated as the difference between the value estimates according to the new and old methodology, it is applied as an additive factor, meaning that the revision is performed so that each value in the time series is added by that factor.

After that, in order to maintain the multivariate structure of the LFS time series and meet the appropriate linear constraints (e.g. to make the sum of the revised data by gender and / or age groups equal to the revised series of totals), additional correction factors were applied in accordance with Eurostat recommendations given at the workshop dedicated to this topic.

Additionally, the justification for choosing this approach in correcting breaks and the reliability of the obtained results were confirmed by applying correlation analysis to the revised time series of the LFS and data on registered employment from the SORS database.

Link of the brochure with detailed explanations is in annex.

2. In 2016  the evaluation system was changed. The Statistical Office of the Republic of Serbia proceeded with this revision in order to overcome the effect of that change and ensure data comparability for the following period with data from 2014 and 2015. From 2014 data are available both according to the old and new system. This makes it possible to measure the impact of different evaluation systems and to apply the calculated index on previous years.

The Labour Force Survey is the most comprehensive continuous research in Serbia. Since 2015, when there was the change in periodicity, interviews have been conducted every week (from Monday to Sunday), where in one week only one subsample is interviewed, and in the following one another subsample, and so on. The respondents provide answers about their employment activity in the week which is the reference week for them.

Type of sample

The LFS uses a two-stage stratified cluster sampling approach. The sample of enumeration areas (cluster of households) was selected at the first stage. A sample of households was selected in each enumeration area at the second stage. Enumeration areas as primary sampling units are stratified according to the type of settlements (town and other) and territory at NSTJ 3 level.

Rotation scheme and sample allocation

The LFS is based on the rotation panel design, by which each household participate in the sample for four times. The rotating scheme 2-2-2 was applied.

For each quarter four subsamples (rotating groups) are allocated. Each quarter (Q) in the sample is included: one new rotating group, two rotating groups from the previous quarter (Q-1) and one rotating group from the same quarter of previous year (Q-3).  Based on the applied rotating scheme, each household and person selected in the sample will be interviewed four times within 18 months, i.e. each household and person is in the sample for two consecutive quarters, then for two quarters out of the sample and again for two consecutive quarters in the sample.

The applied rotation scheme based on the overlapping of the sample for two consecutive quarters, as well as for the same quarter in two consecutive years enables an efficient sampling plan for measuring the changes to the previous quarter and for measuring changes to the same quarter of the previous year.

Proportional sample allocation according to the number of persons aged 15 and over, within the type of settlement and territory, has been slightly corrected in order to obtain more precise estimates on the level of areas.

The transition to the continuous periodicity of the survey required the sample distribution over time. Every subsample allocated for a quarter is uniformly and randomly distributed into 13 weeks, and exceptionally, which happens once in four years when there are 53 observed weeks, the sample for one quarter (first or fourth) is distributed to 14 weeks. This was the case in the fourth quarter of 2015.

Every week during a year is the referent week and households selected in the sample are distributed according to them. The survey of a selected household is conducted over a two-week period after the referent week in which they are distributed, i.e. the survey is conducted continuously  during the whole calendar year.

Every household selected in the sample is interviewed four times within 18  months, i.e. the household is in the sample during two consecutive quarters, then it is out of the sample for two quarters, then the next two quarters it is in the sample again.

The tool for data collection in LFS is the electronic questionnaire, which is both used by interviewers doing the telephone interview (CATI) and those working on the field (CAPI).

Field and telephone interviewers are engaged in the collection of data. They are the main stakeholders in LFS conducting and the success of the survey depends on their work. The realization of LFS is dependent on how they make interviews, are acquainted with the essence of the questions in the questionnaire and on how they interpret them. Their diligence and efforts are also important.

The first interview round is made through personal contact, i.e. interviewer’s visit to the household. The interviewers have laptops with an installed electronic questionnaire. During the first visit, the interviewers record household’s contact telephone in order to carry out the next three interviews through the call-centre. The interviewer collects first socio-demographic information for each household member, and then information about employment status of members aged 15-89. In the next round, the interviewer checks the socio-economic information collected in the first interview, and then she/he gathers information about the employment status for the current quarter.

Until the fourth quarter of 2014 there were two modes of data collection PAPI (personal visits with paper questionnaire) and CATI (computer-assisted telephone interviewing). In the fourth quarter of 2014, PAPI was replaced with CAPI mode of data collection (computer-assisted personal interview).

Participation in the Labour Force Survey is on voluntary basis.

The tool for data collection in the LFS is the electronic questionnaire, which is both used by interviewers doing the telephone interview (CATI) and those working on the field (CAPI). Utilising the electronic questionnaire saves time and money needed for data entry and processing. All the interviewers use the same questionnaire, but logical control (implemented to reduce as much as possible the number of errors in data entry) is not the same for telephone interview and fieldwork. Logical control for CAPI is lighter because it is reckoned that an interviewer should stay on in the household as little time as possible, thus they do not enter the codes of occupations, economic activities and field of education, but only describe the requested information. Coding and complete logical control of fieldwork materials are performed after data entry in the central database located on the server of the Statistical Office of the Republic of Serbia in the Computer Centre by statisticians and engaged supervisors.

The data collected by telephone interview are directly registered in the central database, and then coded. Full logical control is applied for them during data entry.

Logical control recognizes obvious incompatibilities (e.g. a respondent aged 15 who worked for the last time in 1940). If the value is suspect but reasonable, the programme will alert the interviewer to check the entered data and confirm them if they are correct. This way the probability of making this type of errors in data entry is prevented.

In the Labour Force Survey 'depending interviewing' is used, which means that previous answers are used to reduce the response burden and to limit the amount of time used to manually seek out errors. The interviewed persons validate previous answers.

Not applicable.

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