Background
The Labour Force Survey (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 Quarterly Labour Force Survey (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.
Longitudinal data
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.
Updated longitudinal user guide available
An updated version of the Labour Force Survey (LFS) longitudinal user guide was published in 2012 by the Office for National Statistics (ONS). It has been added to LFS longitudinal datasets for 2012, but can also be obtained from the ONS Labour Force Survey - User Guidance webpage. The series documentation available from the Archive to accompany LFS datasets largely consists of the latest version of each volume alongside the appropriate questionnaire for the year concerned. However, LFS volumes are updated periodically by ONS, so users are advised to check the user guidance webpage before commencing analysis.
Additional data derived from the QLFS
The Archive also holds further QLFS series: End User Licence (EUL) quarterly data; Special Licence (SL) access and Secure Data Service access datasets (see below); household datasets (produced twice a year); quarterly, annual and ad hoc module datasets compiled for Eurostat; and some additional annual Northern Ireland datasets.
LFS move from seasonal to calendar quarters
In accordance with European Union regulations, the QLFS moved from seasonal (spring, summer, autumn, winter) quarters to calendar quarters (January-March, April-June, July-September, October-December) in 2006. Subsequently, calendar versions of all datasets in the EUL and SL QLFS series were deposited and the previous seasonal datasets were removed from the Archive's catalogue at the request of ONS. However, some seasonal datasets still exist for the longitudinal series for 2008 and earlier, and ONS advise that, because of the method of construction and the weighting factors used in the datasets, comparison cannot be made between datasets of a calendar and seasonal nature. Time series and longitudinal analysis should only be conducted on datasets of the same type.
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