|Labour Force Survey (LFS)
|Sample survey based
|13 January 2015
The primary purpose of the Labour Force Survey (LFS) is "providing good quality point in time and change estimates for various labour market outputs and related topics” (National Statistics Quality Review (NSQR) of Labour Force Survey 2014). The labour market covers all aspects of people's work, including the education and training needed to equip them for work, the jobs themselves, job-search for those out of work and income from work and benefits.
Output from the LFS is quarterly since 1992. Each quarter’s sample is made up of 5 waves.
The sample is made up of approximately 40,000 responding UK households and 100,000 individuals per quarter. Respondents are interviewed for 5 successive waves at 3-monthly intervals and 20% of the sample is replaced every quarter. The LFS is intended to be representative of the entire population of the UK.
LFS quarterly datasets are provided to government departments and are available to approved researchers via ONS’s Virtual Microdata Laboratory (VML) and the UK Data Archive, Essex University. The UK Data Archive also provides non-disclosive data for public access.
LFS user guidance is also available.
This report contains the following sections:
About the output
How the output is created
Validation and quality assurance
Concepts and definitions
Other information, relating to quality trade-offs and user needs
Sources for further information or advice
This report provides a range of information that describes the quality of the output and details any points that should be noted when using the output.
We have developed Guidelines for Measuring Statistical Quality; these are based upon the five European Statistical System (ESS) Quality Dimensions. This report addresses these quality dimensions and other important quality characteristics, which are:
timeliness and punctuality
coherence and comparability
output quality trade-offs
assessment of user needs and perceptions
accessibility and clarity
More information is provided about these quality dimensions in the following sections.Back to table of contents
(The degree to which the statistical outputs meet users’ needs.)
What the Labour Force Survey (LFS) measures
Main measures include: economic activity and inactivity, all aspects of people’s work, job-search for the unemployed, education and training, income from work and benefits. See LFS User Guide Volume 2 for all LFS measures.
1973 to 1983 biennially 1984 to 1991 annually 1992 to 2006 seasonal quarters (December to February, March to May, June to August, September to November) 2006 to present calendar quarters (January to March, April to June, July to September, October to December).
Approx 40,000 responding UK households per quarter.
Quarterly since 1992.
Postcode Address File and NHS communal accommodation.
Each quarter’s sample is made up of 5 waves. Respondents are interviewed for 5 successive waves at 3-monthly intervals. Approximately 20% of the sample is replaced every quarter. The LFS is intended to be representative of the entire population of the UK. Note that the sample design excludes most communal establishments.
The LFS uses calibration weighting. The weights are formed using a population weighting procedure that involves weighting data to sub-regional population estimates and then adjusting for the estimated age and sex composition by region (income weighted separately).
Estimation to population totals and projections based on the census.
Roll-forward (for one wave only) in LFS Person datasets; additional imputation of missing case information for individuals in LFS Household datasets.
Income outliers filtered out prior to income weighting.
The primary purpose of the LFS is "providing good quality point in time and change estimates for various labour market outputs and related topics” (NSQR Review of Labour Force Survey 2014). The “labour market” covers all aspects of people's work, including the education and training needed to equip them for work, the jobs themselves, job-search for those out of work, and income from work and benefits. LFS User Guide volume 1 provides survey background and methodology.
Users of LFS data often combine them with related data from other sources to provide an overall view of the state of the labour market. One of the most important users of this sort of assessment is the Bank of England's Monetary Policy Committee. Other important users of LFS data are HM Treasury and the Department for Work and Pensions. They are interested in a variety of indicators of the state of the labour market, including the number of people in employment, the number of hours worked and the number of unemployed people (defined according to the International Labour Organisation (ILO)). They often analyse these series by age groups, by regions and by sex.
Other government users include the Department for Business, Energy and Industrial Strategy, the Home Office, the Health and Safety Executive, the Scottish Government, and the Welsh Government.
At the international level, LFS data are used by the European Parliament, Council and Commission, the European Central Bank and DG Employment (Directorate-General for Employment, Social Affairs and Equal Opportunities). It is also used by the Organisation for Economic Co-operation and Development (OECD) and the International Labour Organisation (ILO).
Other users include local authorities, the Trades Union Congress (TUC), the Employer's Association, the Confederation of British Industry, the Institute of Employment Studies, and the Institute for Public Policy Research, the National Institute of Economic and Social Research, the Policy Studies Institute, the Institute for Fiscal Studies, academic researchers, the media and the general public.
Main definitions are the three economic activity groups - employed, unemployed and economically inactive - used in the LFS, which are the standard ILO definitions. It should be noted that although the LFS uses ILO definitions, these definitions are not interpreted and applied in exactly the same way in different countries, however, Eurostat collects data from all member states and adjusts them to produce comparable estimates.
One of the strengths of the LFS is that it has the largest sample size of any household survey and can thus generate robust statistics at regional level. In addition, the sampling errors are small, because the LFS has a single-stage, random sample of addresses. The survey covers a large range of employment-related variables and non-employment-related variables, allowing cross-linking analyses to be undertaken (for example, earnings against educational attainment).
One of the limitations of the LFS is that the sample design provides no guarantee of adequate coverage of any industry, as the survey is not stratified by type of industry. The LFS coverage also omits communal establishments, excepting NHS housing and students in boarding schools and halls of residence. Members of the armed forces are only included if they live in private accommodation. Also, workers under 16 years of age are not covered.
User consultation is undertaken to identify gaps between main user needs (see the Assessment of user needs and perceptions section).
Note: for coverage of smaller geographical areas the Annual Population Survey (APS) enables production of good-quality, annual estimates for relatively small areas of the UK on a rolling quarterly basis. The APS is intrinsically linked to the LFS. Much of the data that comprise the APS dataset come from the main LFS (wave 1 and wave 5 responses are pooled across 4 quarters); the remainder of the APS dataset comes from boost or enhancement surveys in Great Britain. The APS sample design, datasets and data sources are described in Volume 6 (Local Area Data) of the LFS User Guide.
Timeliness and punctuality
(Timeliness refers to the lapse of time between publication and the period to which the data refer. Punctuality refers to the gap between planned and actual publication dates.)
Main labour market statistics are published in the UK Labour market statistical bulletin (LM SB), (previously called Labour Market Statistics First Release) first published in April 1998 (see February 1998 Labour Market Trends article, Improved Labour Market Statistics). The LM SB, which is published monthly, gives prominence to the ILO measure of unemployment, as measured by the LFS over the administrative Claimant Count measure and draws together statistics from a range of sources to provide a more coherent picture of the labour market.
The Claimant Count is not an alternative measure of unemployment.
LFS results in the LM SB are published on a UK basis, 6 weeks after the end of the survey period and relate to the average of the latest 3-month period.
Since April 1998, the Department of Enterprise, Trade and Investment (DETINI) have published a Northern Ireland Labour Market Statistics Release to the same timetable as publication of the Labour market statistical bulletin.
Publication takes place strictly in accordance with published release dates for Labour market statistics, following the Code of Practice for Official Statistics. The publication date has never been missed. Timeliness on a continuous survey such as the LFS should be carefully compared against surveys or administrative series that report on a point or only part of the reference period, particularly in regard to issues around discontinuities in the data (see LFS User Guide Volume 1: LFS Background and Methodology for guidance).
The frequency of LFS data output is:
1973 to 1983 biennially 1984 to 1991 annually 1992 to 2006 seasonal quarters (December to February, March to May, June to August, September to November) 2006 to present calendar quarters (January to March, April to June, July to September, October to December).
For more details on related releases, the GOV.UK release calendar and provides 12 months’ advance notice of release dates. If there are any changes to the pre-announced release schedule, public attention will be drawn to the change and the reasons for the change will be explained fully at the same time, as set out in the Code of Practice for Official Statistics.Back to table of contents
The Labour Force Survey (LFS) covers private households, including persons who are temporarily absent. The resident population comprises persons who regard the sample address as their main address, and also those who have lived in the dwelling for more than 6 consecutive months, even if they do not regard this as their principal dwelling. Persons absent for more than 6 months are not regarded as members of the resident population. A private household comprises one or more persons whose main residence is the same dwelling and/or who share at least one meal per day. Students living in boarding schools and halls of residence are sampled via the private households of their parents. In Great Britain, an additional sample is drawn from persons living in National Health Service accommodation.
The LFS survey year is divided into quarters of 13 weeks. Prior to January 2006, these were seasonal quarters: winter (December to February), spring (March to May), summer (June to August) and autumn (September to November). From January 2006, the LFS has been conducted on the basis of calendar quarters: January to March (Quarter 1), April to June (Quarter 2), July to September (Quarter 3) and October to December (Quarter 4). The change to calendar quarters was in response to the European Union Regulation 1 on the conduct of continuous labour force surveys in all member states.
Four different sampling frames are used in the UK LFS. Great Britain is split into two areas: south of the Caledonian Canal, comprising all of England, Wales and most of Scotland; and north of the Caledonian Canal in Scotland. Northern Ireland has its own sampling frame. A separate list of NHS accommodation in Great Britain is maintained.
For most of Great Britain, the sampling frame is the Royal Mail's Postcode Address File (PAF), a database of all addresses receiving mail. The list is limited to addresses receiving relatively few items of post per day, so as to exclude businesses. Because of the very low population density in the far north of Scotland (north of the Caledonian Canal), telephone directories are used as sampling frames and interviews are carried out by telephone because face-to-face interviews would be too expensive. In Northern Ireland POINTER, which is the government's central register of domestic properties, is used.
In Great Britain, a systematic sample is drawn each quarter from the three sampling bases, which yields 16,640 PAF addresses, 80 telephone numbers for the north of Scotland and nine units of National Health Service housing. As the PAF is broken down geographically, the systematic sampling ensures that the sample is representative at regional level. In Northern Ireland, a simple random sample is drawn, each quarter, from each of the three strata, giving 650 addresses in all. Additionally, 260 additional (“booster”) new addresses are added to the sample in Quarter 2 (April to June) of each year; these are spread equally across the 5 waves. Thus, in any one quarter, a total of about 17,380 addresses are newly-selected in the UK for the main LFS (excluding the Northern Ireland boosters).
Note that two changes made to the design in 2010 mean the LFS samples in Great Britain and also in Northern Ireland are strictly no longer equal probability samples, although the effect of the changes is relatively small. These changes relate to multiple-occupancy addresses and to households found that have only adults aged 75 and over.
From the Quarter 3 (July to September) 2010 survey, only one household has been selected for interview where there was more than one present at the sampled address. The selection of that household is carried out randomly (that is, by use of random numbers). This change has been introduced to help harmonise ONS social surveys. The effect of the change is that any such household now has a lower probability of selection, which is now reflected by it receiving a higher weight then no further waves of interviews are conducted.
The second change in sample design was also introduced for the Quarter 3 2010 interviews. If a household is found that has only adults aged 75 and over, then no further waves of interviews are conducted. This amendment had an immediate effect from its introduction, that is, if a household of all 75 and over occupants was found in any wave in Quarter 2 2010, then no interview was conducted in Quarter 3 2010 or any subsequent quarters. Further details of these changes can be found in the LFS User Guide Volume 1: LFS Background and Methodology.
For the most part, the LFS may be regarded as a single-stage sample of households each quarter, though changes made in 2010 mean this is no longer strictly the case. The geographical ordering of the frame implicitly stratifies the sample, ensuring a geographic spread of addresses. Since all adults within a household are sampled, the person-level survey may be regarded (mainly) as a one-stage cluster sample of people, with the clusters (or primary sampling units) being the households.
A rotation system comprising 5 waves is used. Respondents are interviewed five times at 13-week intervals and one-fifth of the sample is replaced each quarter due to the rotation design. Interviews are carried out on a face-to-face basis (known as Computer Assisted Personal Interviews (CAPI)), with the help of portable computers, for the majority interviews in the first wave.
In the far north of Scotland (north of the Caledonian Canal), for around 10 to 20% of interviews in the first wave (from January 2011) and for all in the second to fifth waves wherever possible, interviews are carried out by telephone, known as Computer Assisted Telephone Interviews (CATI). Further details of the methodology used in the LFS can be found in the LFS User Guide Volume 1: LFS Background and Methodology.
If a household is unavailable for interview, but was interviewed in the previous wave, responses from the previous wave are rolled forward. This is referred to as imputation. Imputation is carried out to minimise non- response bias in estimates, while simultaneously improving precision by boosting the sample size. The rationale is that most LFS variables do not change from one quarter to another for most people. Responses are rolled forward for one wave only. Data are not rolled forward after a second consecutive non-response. In the LFS Performance and Quality Monitoring Report (PQM), tables and charts (at person or household level) containing responses that have been rolled forward from the previous wave are denoted by the term “including imputed”.
Tables and charts that do not contain responses that have been rolled forward from the previous wave are denoted by the term “excluding imputed”.
LFS Household datasets contain household members who did not respond to the current wave of interviewing, but their household did. In cases where no proxy information was collected for these people or where no information was collected for them in the previous wave, their data are imputed with reference to responders with similar personal characteristics (age, sex and economic status).
Method of calculating response rates
The response rate indicates how many interviews were achieved as a proportion of those eligible for the survey. The formula used is as follows:
RR equals (FR plus PR) divided by (FR plus PR plus OR plus CR plus RHQ plus NC plus RRI)
where RR is response rate, FR is full response, PR is partial response, OR is outright refusal, CR is circumstantial refusal, RHQ is refusal to HQ, NC is non-contact, RRI is refusal to re-interview (applies to waves 2 to 5 only).
Method of weighting
The LFS uses calibration weighting to assign a calibration weight wk to each responding individual k. These
calibration weights are set to sum to a set of calibration totals within calibration groups - for example, the weights of all 18-year old males in an LFS dataset (a calibration group) will sum to the population total of eligible 18-year old males in the UK (a calibration total) at the time the survey was taken. Calibration weighting typically involves calculating a design weight, making adjustments for non-response and finally calibration to population totals.
The LFS assigns a calibration weight to all responding or imputed individuals, but does not assign a weight to individuals whose economic activity is unknown (so non-responders do not get a weight). Standard LFS practice in the case of individuals dropping out between waves is to roll their data forward by 1 quarter - this is a form of imputation and these individuals receive a weight.
Further details of the weighting methodology used in the LFS can be found in the LFS User Guide Volume 1.
Calibration is to population estimates within local authorities.
At certain points in time, Office for National Statistics (ONS) releases revised population estimates. LFS conducts reweighting exercises and re-releases of data and labour market estimates. In 2014, there was a major reweighting exercise, of data between 2001 to 2014, based on revised population estimates produced from the 2011 Census.
Definitions of response outcome categories
A full response denotes a household in which each household member has answered all applicable questions.
A partial response denotes a household in which questions were not completed because someone refused to be interviewed, refused part way through the questionnaire, or refused to let someone else answer on his or her behalf. However, at least one question block must have been completed. If only part information has been collected for a one-person household, it is coded as a refusal or non-contact.
An outright refusal is a household that refuses to respond to the survey and the interviewer feels that there is no chance of an interview at the current or in any future wave.
A circumstantial refusal is a household where the respondent refuses to respond because of a temporary circumstance (for example, going on holiday, too busy during the field period). A circumstantial refusal enables an interviewer to call back at the next wave.
A refusal to HQ is a household that contacts headquarters to refuse to participate in the survey in response to the advance letter.
A non-contact arises when an address is occupied but where it has not been possible to contact any member of the household in the field period.
A refusal to re-interview is a household that takes part in the survey (at one or more of waves 1 to 4) but which, when asked to take part in the next wave (waves 2 to 5), refuses.
Method of calculating income response rates
The income question is asked at wave 1 and wave 5 only. Individuals aged 16 to 69 who are in employment in the reference week (information about respondents' activities in a 7 day period, which ends on a Sunday) form the sub-set of respondents who are eligible for these questions. The percentage response rates for the income questions are based on all eligible in-scope respondents at wave 1 and all eligible in-scope respondents at wave 5. The total response rate is the cumulative response rate for income for the quarter (wave 1 and wave 5), based on all eligible, in-scope respondents.
The LFS has to complete fieldwork to a tight timetable and interview as many of the sampled households as possible, which leaves limited time for recalls. LFS interviewers try to interview every adult (aged 16 and over) in each sampled household. However, when a household member is unavailable for interview, interviewers accept information by proxy from another responsible adult in the household. The proxy respondents are normally people living with a partner who respond on behalf of their partner and parents who respond on behalf of their adult offspring who live with them, who are at boarding school or who are in university halls of residence.
Attrition is the term applied to respondents who begin the survey but subsequently drop out. It has been known for some time that these respondents tend to have different characteristics compared with those who remain in all waves of the survey and can, therefore, result in attrition bias. For example, if respondents in a particular age band have a higher tendency to drop out (attrition rate) than respondents in other age bands, then they will be under-represented in subsequent waves of the survey and in survey estimates.
Statistical disclosure control methodology is also applied to the LFS data. This ensures that information attributable to an individual is not disclosed in any publication and that confidentiality of respondents is protected in datasets. The Code of Practice for Official Statistics and specifically Principle 5, Confidentiality, sets out the principles for protecting data from being disclosed. The Statistics and Registration Service Act 2007 includes data confidentiality regulations which apply to ONS.Back to table of contents
(The degree of closeness between an estimate and the true value.)
The main threats to the accuracy of the data are sampling error and non-sampling error, where non-sampling error includes: coverage error, non-response error, measurement error and processing error.
Many of the sources of non-sampling error are difficult to measure. However, in the Labour Force Survey (LFS) Performance and Quality Monitoring Report (PQM), detailed response rates for all waves of the survey are published, as well as an overall response rate, including time series. Response rates by regions for each wave during the particular quarter, proxy response rates, response rates for income questions by National Statistics (NS) socio-economic classification and attrition rates are also published in the PQM.
Surveys, such as the LFS, provide estimates of population characteristics rather than exact measures. In principle, many random samples could be drawn and each would give different results, due to the fact that each sample would be made up of different people, who would give different answers to the questions asked. The spread of these results is the sampling variability, which generally reduces with increasing sample size. Confidence intervals are used to present the sampling variability. For example, with a 95% confidence interval, it is expected that in 95% of the survey samples, the resulting confidence interval will contain the true value that would be obtained by surveying the whole population.
In its PQM the LFS routinely publishes details of achieved sample sizes in terms of achieved number of household and person interviews, and sampling variability for estimates of main variables, where it is expected that in 95% of samples the range would contain the true value. The sampling variability gives the range above and below the estimate at a 95% confidence interval. The PQM also notes changes to the LFS questionnaire and resulting outputs.
Coherence and comparability
(Coherence is the degree to which data that are derived from different sources or methods, but refer to the same topic, are similar. Comparability is the degree to which data can be compared over time and domain, for example, geographic level.)
The LFS began in 1973 and it was carried out every 2 years until 1983. Between 1984 and 1991, data were collected annually and the survey has been running in its present form, with quarterly sampling, since spring 1992 with a change from seasonal to calendar quarters in 2006. It is carried out under European Union regulations, which specify the way in which the survey should be conducted, the quality of the results that member states supply to Eurostat and the timetable for supplying results. Although the LFS began as a survey designed to meet international obligations, its primary purpose is now "providing good quality point in time and change estimates for various labour market outputs and related topics”.
The LFS is one of a number of sources of data about the labour market. Some sources provide data that overlap with LFS data on employment, unemployment and earnings. We have published guidance about the strengths and limitations of each source in relation to these topics and have indicated which source is the most appropriate for different purposes.
The LFS is the source we recommend for certain employment-related statistics (for example, estimates of the number of people in employment or unemployed). The LFS is also a unique source of comprehensive, coherent information about economic inactivity.
A non-LFS source, the workforce jobs (WFJ) series provides estimates of the number of jobs in the UK economy and is the source we recommend for both the number of jobs and the industrial composition of jobs. Workforce jobs consist of the sum of employee jobs, self-employment jobs, jobs in the armed forces and government-supported trainees. Civilian workforce jobs are available by geographical region, sex and broad industry. Total workforce jobs are available by sex and broad industry.or estimates of change in earnings (for example, pay growth in the economy), a non-LFS source, the average weekly earnings (AWE) (formerly the Average Earnings Index) is the most suitable source. It provides industry and whole-economy information, but excludes small employers, the self-employed and government-supported trainees. Pay, commission, bonuses, overtime and pay award arrears are included, but redundancy payments and benefits in kind are excluded.
The Annual Survey of Hours and Earnings (ASHE) includes information about the levels, distribution and make-up of earnings and hours worked for employees in different occupations, industries, ages and regions. It should be used when the information required is not available from the AWE
(such as for occupational groups, or regional analyses) and is the preferred source of the earnings of full-time employees, and of the average hourly earnings of all employees. The LFS earnings information is less accurate, because - unlike business surveys in which businesses consult payroll details - the LFS asks respondents to recall earnings details that may not be to hand and in consequence are subject to higher recording error. LFS earnings data should be used when the information is not available from the AWE or from ASHE and is the preferred source of data about the earnings of part-time and low-paid employees.Back to table of contents
(Concepts and definitions describe the legislation governing the output, and a description of the classifications used in the output.)
The Labour Force Survey (LFS) is a legal requirement of the European Union. The definitions of the main economic activity groups - the economically active, comprising the employed and the unemployed, and the economically inactive - which are used in the LFS, are standard International Labour Organisation (ILO) definitions.
The economically active are defined as those aged 16 and over, who are either employed or unemployed in the survey reference week.
The employed are defined as those aged 16 and over, who are in employment if they did at least 1 hour of work in the reference week (as an employee, as self-employed, as unpaid workers in a family business, or as participants in government-supported training schemes) and those who had a job that they were temporarily away from (for example, if they are on holiday).
The unemployed are defined as those aged 16 and over, who are without work, have actively sought work in the last 4 weeks and are available to start work in the next 2 weeks; or are out of work but have found a job and are waiting to start it within the next 2 weeks.
The economically inactive are defined as those aged 16 and over who are neither in employment nor unemployed. This group includes, for example, all those who are looking after a home or family, have a long-term illness or disability that prevents them working, or are retired.
Unpaid family workers also belong to the employed category and are those who are doing unpaid work in a family business.Back to table of contents
Output quality trade-offs
(Trade-offs are the extent to which different dimensions of quality are balanced against each other.) Please see the above section on Coherence and comparability.
In 2014, the Office for National Statistics (ONS) conducted a National Statistics Quality Review of Labour Force Survey 2014. This review assessed current methods against three quality dimensions and made recommendations about potential changes.
Assessment of user needs and perceptions
(The processes for finding out about user and users, and their views on the statistical products.)
External users of Labour Force Survey (LFS) data include government departments, non-government departments, academics and the public.
The views of external and internal LFS stakeholders and sponsors are regularly sought and 6-monthly Steering Group consultation meetings are held. The LFS also works closely with the Economic and Social Data Service (ESDS) to ensure that the wider external user views are accessed. The LFS attends the Household and Labour Market Division (HLMD) quarterly liaison meeting with main external stakeholders.
The LFS routinely consults with internal ONS divisional users of the LFS. The LFS and HLMD hold regular internal liaison meetings.Back to table of contents
Accessibility and clarity
(Accessibility is the ease with which users are able to access the data, also reflecting the format in which the data are available and the availability of supporting information. Clarity refers to the quality and sufficiency of the release details, illustrations and accompanying advice.)
Analysts wishing to conduct analysis of Labour Force Survey (LFS) data can apply for access to LFS microdata through various routes, aligned to the policy of Open Data. These routes, for different types of data user, are as follows:
- highly disaggregated data, which cover a wealth of data for local areas (utilising Annual Population Survey (APS) data), are available free on the nomis website
- a comprehensive dataset containing non-disclosive variables may be accessed through the UK Data Archive End User Licence
Applicants who acquire Approved Researcher status may access the data through:
- ONS’s Virtual Microdata Laboratory (VML); this provides the opportunity to conduct detailed analysis, in a controlled environment
- UK Data Archive, Special Licence; this provides the opportunity to conduct analysis of selected variables through datasets downloaded by the applicant
The LFS Data Service provides advice, can provide some ad hoc analysis of data for a fee and can be contacted by phone: +44 (0) 1633 455272 or email email@example.com.
Labour market data, including data from the LFS, are published every month and include text, tables and charts. The data are widely available, generally free of charge, through a range of media. Labour market statistical bulletin and time series data contained within the releases are available to download, free of charge.
Our recommended format for accessible content is a combination of HTML web pages for narrative, charts and graphs, with data being provided in usable formats such as CSV and Excel. Our website also offers users the option to download the narrative in PDF format. In some instances other software may be used, or may be available on request. Available formats for content published on our website but not produced by us, or referenced on our website but stored elsewhere, may vary. For further information please refer to the contact details at the beginning of this report.
For information regarding conditions of access to data, please refer to the following links:
Terms and conditions (for data on the website)
In addition to this quality and methodology information, further information is available in the background notes of the Labour market statistical bulletin and in the Guide to labour market statistics and LFS user guidance.Back to table of contents