Labour Force Survey Five-Quarter Longitudinal Dataset, January 2004 - March 2005

<p><b>Background</b><br>
The <i>Labour Force Survey</i> (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 <i>Quarterly Labour Force Survey</i> (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.<br>
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<b>Longitudinal data</b><br>
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.<br><br>
<b>LFS Documentation</b><br>
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 <a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/labourforcesurveyuserguidance" title="Labour Force Survey - User Guidance" target="_blank">Labour Force Survey - User Guidance</a> pages before commencing analysis. <b>This is especially important for users of older QLFS studies, where information and guidance in the user guide documents may have changed over time.</b><br></p><p><span style="font-weight: bold;">Occupation data for 2021 and 2022 data files</span><br></p><p>The ONS has identified an issue with the collection of some occupational data in 2021 and 2022 data files in a number of their surveys. While they estimate any impacts will be small overall, this will affect the accuracy of the breakdowns of some detailed (four-digit Standard Occupational Classification (SOC)) occupations, and data derived from them. Further information can be found in the ONS article published on 11 July 2023: <a title="Revision of miscoded occupational data in the ONS Labour Force Survey, UK: January 2021 to September 2022" href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/articles/revisionofmiscodedoccupationaldataintheonslabourforcesurveyuk/january2021toseptember2022" style="background-color: rgb(255, 255, 255);">Revision of miscoded occupational data in the ONS Labour Force Survey, UK: January 2021 to September 2022</a>.</p><p><span style="font-weight: bold;">2022 Weighting</span></p><p>The population totals used for the latest LFS estimates use projected growth rates from Real Time Information (RTI) data for UK, EU and non-EU populations based on 2021 patterns. The total population used for the LFS therefore does not take into account any changes in migration, birth rates, death rates, and so on since June 2021, and hence levels estimates may be under- or over-estimating the true values and should be used with caution. Estimates of rates will, however, be robust.</p> For the second edition (June 2012), a new data file has been deposited, weighted to 2010 population figures. A new version of the longitudinal user guide has been added to the documentation. <br>
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<p><b>背景</b><br>
劳动力调查（Labour Force Survey，LFS）是一项独特的信息来源，采用就业、失业及经济不活跃状态的国际定义，涵盖职业、培训、工作时长及16岁及以上家庭成员个人特征等广泛相关主题，用于为社会、经济及就业政策提供依据。LFS于1973年至1983年每两年开展一次；1984年至1991年改为每年开展，包含全年季度调查及春季季度补充调查（数据按季节性收集）。1992年起开始提供季度数据，季度样本量与此前年度数据大致相当，此后该调查被称为季度劳动力调查（Quarterly Labour Force Survey，QLFS）。1994年12月起，北爱尔兰的数据收集转为完整季度周期，以与英国其他地区保持一致，因此QLFS覆盖全英国（不过英国数据档案馆也保存了部分北爱尔兰年度LFS数据集）。关于QLFS背景的更多信息可参见相关文档。<br>
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<b>纵向数据</b><br>
LFS对每个样本家庭连续追踪五个季度，每季度替换五分之一样本。主调查原本旨在生成横截面数据（cross-sectional data），但目前已将个体记录关联起来以提供纵向数据（longitudinal data）。纵向数据包含两类关联数据集，均采用加权方法调整非响应偏差：两季度数据集关联连续两波的数据，五季度数据集关联一整年的数据（例如2010年1月至2011年3月，含首尾），涵盖所有五波数据。纵向数据系列可追溯至1992年冬季。通过关联记录构建纵向维度，可获取不同劳动力类别（就业、失业、经济不活跃）之间随时间的总流动信息，从而详细了解类别间流动的人群特征。此外，纵向信息有助于监测政府政策效果，可用于跟踪受特定政策举措影响人群的后续活动及状况，并与其他人群组进行比较。然而，纵向关联过程中存在可能扭曲数据的方法学问题，英国国家统计局（Office for National Statistics，ONS）持续研究这些问题，并建议谨慎呈现结果，必要时在输出中加入警示说明。<br><br>
<b>LFS文档</b><br>
档案馆提供的LFS数据集配套文档主要包括各用户指南卷的最新版本及对应年份的问卷。但ONS会定期更新文档卷，因此建议用户在开始分析前，查阅ONS <a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/labourforcesurveyuserguidance" title="Labour Force Survey - User Guidance" target="_blank">劳动力调查用户指南</a>页面的最新文档。<b>这对较早QLFS研究的用户尤为重要，因为用户指南中的信息和指导可能随时间变化。</b><br></p><p><span style="font-weight: bold;">2021及2022年数据文件中的职业数据</span><br></p><p>ONS发现其多项调查中2021及2022年数据文件的部分职业数据存在收集问题。尽管整体影响估计较小，但会影响部分详细（四位数标准职业分类（Standard Occupational Classification，SOC））职业的细分准确性及衍生数据。更多信息可参见ONS 2023年7月11日发布的文章：<a title="Revision of miscoded occupational data in the ONS Labour Force Survey, UK: January 2021 to September 2022" href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/articles/revisionofmiscodedoccupationaldataintheonslabourforcesurveyuk/january2021toseptember2022" style="background-color: rgb(255, 255, 255);">英国ONS劳动力调查中错误编码职业数据的修订：2021年1月至2022年9月</a>。</p><p><span style="font-weight: bold;">2022年加权处理</span></p><p>最新LFS估计所用的人口总数，采用基于2021年模式的英国、欧盟及非欧盟人口实时信息（Real Time Information，RTI）数据预测增长率。因此，LFS使用的总人口未考虑2021年6月以来移民、出生率、死亡率等变化，水平估计值可能低估或高估真实值，需谨慎使用；但比率估计值具有可靠性。</p>第二版（2012年6月）新增了按2010年人口数据加权的存档文件，并在文档中添加了新版纵向用户指南。<br>
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