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.
Household datasets
The LFS household datasets have been produced twice a year (April-June and October-December) from the corresponding quarter's individual-level data. The household datasets include all the usual variables found in the individual-level datasets, with the exception of those relating to income, and are intended to facilitate the analysis of the economic activity patterns of whole households. It is recommended that the existing individual-level LFS datasets continue to be used for any analysis at individual level, and that the LFS household datasets be used for analysis involving household or family-level data. From January 2011, a pseudonymised household identifier variable (HSERIALP) is also included in the main quarterly LFS dataset instead.
Change to coding of missing values for household series
From the April-June 1997 household quarter onwards, users should note that all missing values in the data have been set to one '-10' category instead of the previous separate '-8' and '-9' categories. The ONS has introduced a new imputation process for the LFS household datasets and it has thus been necessary to code the missing values into one new combined category ('-10'), to avoid over-complication. The '-10' categorisation is in line with the Annual Population Survey household series. The change was applied to the back series at the time of the April-June 2010 household quarter deposit, to ensure continuity for analytical purposes. It only applies to the household data, and there are no current plans to extend it to other LFS series.
LFS Documentation
The 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 ONS LFS User Guidance page before commencing analysis.
Additional data derived from the QLFS
The Archive also holds further QLFS series: End User Licence (EUL) quarterly datasets; Special Licence access and Secure Data Service access datasets; two-quarter and five-quarter longitudinal datasets; 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 LFS moved from seasonal (spring, summer, autumn, winter) quarters to calendar quarters (January-March, April-June, July-September, October-December) in 2006. Household datasets are therefore released for each April-June and October-December quarter. Seasonal datasets from 1997 (April-June quarters) and 2004 (October-December quarters) onwards that had been replaced by calendar quarters were withdrawn from the Archive catalogue at the request of ONS. The 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. Further information on the seasonal to calendar quarter change and its impact on LFS data may be found in the following article:
Madouros, V. (2006) Impact of the switch from seasonal to calendar quarters in the Labour Force Survey, London: ONS.
Household data weighting:
Household datasets from 2010 onwards are weighted to 2011 population figures. Those from late 2006 onwards are weighted to 2009 population figures, apart from April-June quarters from 1997-2006, and October-December quarters for 2004-2005, which remain weighted to 2007-2008 figures. Prior to these, data are weighted to Census 2001 figures or earlier; users should consult the individual datasets for details.
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For the second edition (October 2008), the data were reweighted using the latest population estimates (2007-2008). The file contains a new household weighting variable, phhwt07, accordingly. In addition, variables Doby, Dobm, Soc2kap, Soc2kl, Soc2kr and Soc2ks have been removed, and Ageeul added (a single year of age variable is also present). Further details about the reweighting project may be found in the documentation.
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