Labour Force Survey Two-Quarter Longitudinal Dataset, October 2019 - March 2020

<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> <br> <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><span style="font-weight: bold;">New reweighting policy</span><br>Following the <a href="http://doc.ukdataservice.ac.uk/doc/8343/mrdoc/pdf/biennial_lfs_aps_reweighting_policy.pdf" target="_blank" style="background-color: rgb(255, 255, 255);">new reweighting policy</a><a href="http://doc.ukdataservice.ac.uk/doc/8343/mrdoc/pdf/biennial_lfs_aps_reweighting_policy.pdf" target="_blank" style="background-color: rgb(255, 255, 255);"></a> ONS has reviewed the latest population estimates made available during 2019 and have decided not to carry out a 2019 LFS and APS reweighting exercise. Therefore, the next reweighting exercise will take place in 2020. These will incorporate the 2019 Sub-National Population Projection data (published in May 2020) and 2019 Mid-Year Estimates (published in June 2020). It is expected that reweighted Labour Market aggregates and microdata will be published towards the end of 2020/early 2021.<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">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> <br> <b> Additional data derived from the QLFS</b><br> 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. <br> <br> <b>Variables DISEA and LNGLST</b><br> 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. <br> <br> An article explaining the quality assurance investigations that have been conducted so far is available on the <a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/analysisofthediscontinuityinthelabourforcesurveydisabilitydataapriltojune2017tojulytoseptember2017" target="_blank">ONS Methodology</a> webpage. For any queries about Dataset A08 please email [e-mail].<br> <br> <span style="font-weight: bold;">Latest Edition Information </span><br>For the fifth edition (August 2021), a new version of the data file was deposited, with the 2020 longitudinal weight included.<br>

<b>背景</b><br><i>劳动力调查（Labour Force Survey, LFS）</i>是一套独特的信息来源，采用国际通用的就业、失业及经济非活动状态定义，涵盖职业、培训、工作时长以及16岁及以上家庭成员的各类个人特征等广泛相关主题。该调查用于为社会、经济与就业政策制定提供参考。<br>LFS最初于1973年至1983年间以两年期为周期开展。1984年至1991年间，调查改为年度开展，包含全年进行的季度调查与春季季度的增补调查，此后数据按季度采集。自1992年起，季度数据正式发布，季度样本规模大致与此前年度数据的样本规模相当，该调查自此更名为<i>季度劳动力调查（Quarterly Labour Force Survey, QLFS）</i>。1994年12月起，北爱尔兰的数据采集转为完整的季度周期，与英国其他地区保持一致，自此QLFS覆盖全英国（不过英国数据档案馆仍留存有部分额外的年度北爱尔兰LFS数据集）。关于QLFS背景的更多信息可参阅相关文档。<br><br><b>纵向数据</b><br>LFS会将每个抽样家庭连续保留五个季度，每季度更换五分之一的样本。最初的主调查设计用于生成横截面数据，但目前已将每个受访者的相关数据进行关联，以提供纵向信息。纵向数据包含两类通过加权方法调整无应答偏差后生成的关联数据集：两季度数据集关联连续两个调查波次的数据，五季度数据集则覆盖一整年（例如2010年1月至2011年3月，含首尾月份），包含全部五个波次的数据。完整的纵向数据序列可追溯至1992年冬季。<br>通过关联记录构建纵向维度，例如可以获取不同劳动力市场分类（就业、失业及经济非活动状态）间随时间变化的总流动量信息，从而详细呈现于各类劳动力状态间切换的人群情况。此外，纵向信息有助于监测政府政策的实施效果，可用于追踪受特定政策举措影响人群的后续活动与境况，并与其他人口群体进行对比。不过，这种纵向关联可能会引入方法学问题，从而扭曲数据结果。英国国家统计局（Office for National Statistics, ONS）仍在对这些问题开展研究，并建议在呈现结果时需谨慎考量，必要时需在输出结果中附带相关警示说明。<br><br><span style="font-weight: bold;">新加权政策</span><br>遵循<a href="http://doc.ukdataservice.ac.uk/doc/8343/mrdoc/pdf/biennial_lfs_aps_reweighting_policy.pdf" target="_blank">新加权政策</a>，ONS对2019年期间发布的最新人口估算数据进行了评估，并决定不再开展2019年LFS与年度人口调查（Annual Population Survey, APS）的加权工作。因此，下一次加权工作将于2020年启动，届时将纳入2019年地方人口预测数据（2020年5月发布）与2019年年中人口估算数据（2020年6月发布）。预计经加权处理的劳动力市场汇总数据与微观数据将于2020年末/2021年初发布。<br><br><b>LFS文档</b><br>档案馆配套LFS数据集的文档主要包含各年度用户指南手册的最新版本，以及对应年度的调查问卷。不过，ONS会定期更新用户指南手册，因此建议用户在开展分析前，先登录ONS的<a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/labourforcesurveyuserguidance" title="Labour Force Survey - User Guidance">劳动力调查 - 用户指南</a>页面查看最新文档。<b>这一点对于使用老旧QLFS数据集的用户尤为重要，因为用户指南中的信息与指引可能已随时间发生变化。</b><br><br><b>QLFS衍生附加数据</b><br>档案馆还留存有其他QLFS系列数据集：最终用户许可（End User Licence, EUL）季度数据、安全访问数据集、家庭数据集、为欧洲统计局（Eurostat）编制的季度、年度及专项模块数据集，以及部分额外的年度北爱尔兰数据集。<br><br><b>变量DISEA与LNGLST</b><br>因2017年4月至6月与2017年7月至9月间存在明显数据断层，ONS曾暂停的A08数据集（残疾人劳动力市场状况）现已恢复可用。鉴于此次数据断层及现阶段调查结果尚不明确，在对2017年4月至6月的数据与后续时间段的数据进行对比时需格外谨慎。此外，用户需注意，该数据集的估算值未经过季节性调整，因此季度间的部分变化可能源于季节性因素。ONS将于2018年11月发布2018年7月至9月的估算数据时，就该数据集历史对比的后续建议作出说明。<br><br>一篇介绍截至目前已开展的质量保证调查工作的文章，可登录ONS的<a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/analysisofthediscontinuityinthelabourforcesurveydisabilitydataapriltojune2017tojulytoseptember2017" target="_blank">方法学</a>网页查阅。若对A08数据集有任何疑问，请发送邮件至[e-mail]。<br><br><span style="font-weight: bold;">最新版本信息</span><br>在第五版（2021年8月）中，档案馆已存入更新后的数据文件，其中包含2020年纵向权重。