DOI: 10.5255/ukda-sn-7844-3
title: Labour Force Survey Two-Quarter Longitudinal Dataset, April - September, 2015
title: Labour Force Survey Two-Quarter Longitudinal Datasets, 1992-
title: QLFS

description: For the third edition (August 2017) a new version of the data file, weighted to 2017 population figures, was deposited. 
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 &lt;b&gt;Background&lt;/b&gt;&lt;br&gt;
The &lt;i&gt;Labour Force Survey&lt;/i&gt; (LFS) is a unique source of information using international definitions of employment and unemployment and economic inactivity, together with a wide range of related topics such as occupation, training, hours of work and personal characteristics of household members aged 16 years and over. It is used to inform social, economic and employment policy. The LFS was first conducted biennially from 1973-1983. Between 1984 and 1991 the survey was carried out annually and consisted of a quarterly survey conducted throughout the year and a 'boost' survey in the spring quarter (data were then collected seasonally).  From 1992 quarterly data were made available, with a quarterly sample size approximately equivalent to that of the previous annual data. The survey then became known as the &lt;i&gt;Quarterly Labour Force Survey&lt;/i&gt; (QLFS). From December 1994, data gathering for Northern Ireland moved to a full quarterly cycle to match the rest of the country, so the QLFS then covered the whole of the UK (though some additional annual Northern Ireland LFS datasets are also held at the UK Data Archive).  Further information on the background to the QLFS may be found in the documentation.&lt;br&gt;
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&lt;b&gt;Longitudinal data&lt;/b&gt;&lt;br&gt;
The LFS retains each sample household for five consecutive quarters, with a fifth of the sample replaced each quarter. The main survey was designed to produce cross-sectional data, but the data on each individual have now been linked together to provide longitudinal information. The longitudinal data comprise two types of linked datasets, created using the weighting method to adjust for non-response bias. The two-quarter datasets link data from two consecutive waves, while the five-quarter datasets link across a whole year (for example January 2010 to March 2011 inclusive) and contain data from all five waves. A full series of longitudinal data has been produced, going back to winter 1992. Linking together records to create a longitudinal dimension can, for example, provide information on gross flows over time between different labour force categories (employed, unemployed and economically inactive). This will provide detail about people who have moved between the categories. Also, longitudinal information is useful in monitoring the effects of government policies and can be used to follow the subsequent activities and circumstances of people affected by specific policy initiatives, and to compare them with other groups in the population. There are however methodological problems which could distort the data resulting from this longitudinal linking. The ONS continues to research these issues and advises that the presentation of results should be carefully considered, and warnings should be included with outputs where necessary.&lt;br&gt;
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&lt;b&gt;LFS Documentation&lt;/b&gt;&lt;br&gt;
The documentation available from the Archive to accompany LFS datasets largely consists of the latest version of each user guide volume alongside the appropriate questionnaire for the year concerned. However, volumes are updated periodically by ONS, so users are advised to check the latest documents on the ONS &lt;a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/labourforcesurveyuserguidance" title="Labour Force Survey - User Guidance"&gt;Labour Force Survey - User Guidance&lt;/a&gt; pages before commencing analysis. &lt;b&gt;This is especially important for users of older QLFS studies, where information and guidance in the user guide documents may have changed over time.&lt;/b&gt;&lt;br&gt;
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&lt;b&gt; Additional data derived from the QLFS&lt;/b&gt;&lt;br&gt;
The Archive also holds further QLFS series: End User Licence (EUL) quarterly data; Secure Access datasets; household datasets; quarterly, annual and ad hoc module datasets compiled for Eurostat; and some additional annual Northern Ireland datasets. &lt;br&gt;
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&lt;b&gt;Variables DISEA and LNGLST&lt;/b&gt;&lt;br&gt;
Dataset A08 (Labour market status of disabled people) which ONS suspended due to an apparent discontinuity between April to June 2017 and July to September 2017 is now available. As a result of this apparent discontinuity and the inconclusive investigations at this stage, comparisons should be made with caution between April to June 2017 and subsequent time periods.  However users should note that the estimates are not seasonally adjusted, so some of the change between quarters could be due to seasonality. Further recommendations on historical comparisons of the estimates will be given in November 2018 when ONS are due to publish estimates for July to September 2018. &lt;br&gt;
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An article explaining the quality assurance investigations that have been conducted so far is available on the &lt;a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/analysisofthediscontinuityinthelabourforcesurveydisabilitydataapriltojune2017tojulytoseptember2017" target="_blank"&gt;ONS Methodology&lt;/a&gt; webpage. For any queries about Dataset A08 please email Labour.Market@ons.gov.uk.&lt;br&gt;
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