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-style: italic;">Latest Edition Information </span><br>For the third edition (November 2020), as a result of the new method of data collection due to the coronavirus pandemic, the weighting has been calibrated for tenure to mitigate the impact of the non-response bias; users are advised to read more about the change in the "Coronavirus and its impact on the Labour Force Survey" article which is part of the study's documentation.<br>

<b>背景</b><br> <i>劳动力调查（Labour Force Survey, LFS）</i>是采用国际通用的就业、失业及经济非活动状态（economic inactivity）定义的独特信息来源，涵盖职业、培训、工作时长以及16岁及以上家庭成员的个人特征等多类相关主题，可为社会、经济与就业政策制定提供决策参考。LFS最初于1973年至1983年间每两年开展一次。1984年至1991年期间，调查转为年度实施，包含全年开展的季度调查以及春季季度的「补充」调查（彼时数据按季度采集）。1992年起，季度数据正式对外发布，季度样本量大致等同于此前的年度样本量，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，以匹配英国其他地区，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北爱尔兰年度LFS数据集）。有关QLFS背景的更多详情可查阅相关文档。<br><br> <b>纵向数据</b><br> LFS会将每个样本家庭保留连续五个季度，每季度更换五分之一的样本。初始调查设计旨在生成截面数据，但目前已将每个个体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回应偏差的关联数据集：两季度数据集关联连续两轮调查的数据，五季度数据集则覆盖完整一年（例如2010年1月至2011年3月，含首尾），涵盖全部五轮调查的数据。完整的纵向数据序列可追溯至1992年冬季。通过关联记录构建纵向维度，例如可提供不同劳动力类别（就业、失业及经济非活动状态）间随时间变化的总流量信息，从而详细刻画在各类别间流动的人群。此外，纵向信息可用于监测政府政策的实施效果，追踪受特定政策举措影响人群的后续活动与处境，并与其他人口群体进行对比。不过，纵向数据关联过程可能存在方法学问题，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处理，必要时需在输出结果中附带警示说明。<br><br><span style="font-weight: bold;">新加权调整政策</span><br>根据<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);">新加权调整政策</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已对2019年发布的最新人口估算数据进行复盘，决定不再针对2019年LFS与年度人口调查（Annual Population Survey, APS）开展加权调整工作。下一次加权调整工作将于2020年进行，将纳入2019年地方人口预测数据（2020年5月发布）与2019年中期人口估算数据（2020年6月发布）。预计经加权调整的劳动力市场汇总数据与微观数据将于2020年末至2021年初发布。<br> <br> <b>LFS文档资料</b><br> 英国数据档案馆提供的配套LFS数据集文档，主要包含各年度对应用户指南手册的最新版本以及相应的调查问卷。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>页面查阅最新文档。<b>对于老旧QLFS数据集的用户而言，这一点尤为重要，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、为欧盟统计办公室（Eurostat）编制的季度、年度及临时模块数据集，以及部分额外的北爱尔兰年度数据集。 <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月间存在明显数据间断，ONS曾暂停发布数据集A08（残疾人劳动力市场状况），目前该数据集已恢复可用。鉴于此次数据间断及现阶段调查结果仍不明确，在对2017年4月至6月与后续时段的数据进行对比时需格外谨慎。同时需注意，此类估算数据未进行季节性调整，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，针对历史数据对比提供进一步建议。 <br> <br> 一篇介绍目前已开展的质量保证调查工作的文章，可在ONS的<a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/analysisofthediscontinuityinthelabourforcesurveydisabilitydataapriltojune2017tojulytoseptember2017" target="_blank">方法学页面</a>查阅。若对数据集A08有任何疑问，请发送邮件至[e-mail].<br> <br> <span style="font-style: italic;">最新版本信息</span><br>对于2020年11月发布的第三版数据，因新冠疫情导致数据采集方式发生变化，已针对任职年限（tenure）指标进行加权校准，以缓解无回应偏差带来的影响；建议用户查阅研究文档中《新冠疫情及其对劳动力调查的影响》一文，了解此次调整的更多详情。<br>