Labour Force Survey Two-Quarter Longitudinal Dataset, January - June, 2013

<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><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> 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>
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<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>
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<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>
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<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>
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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>
</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> <div><span style="font-style: italic;">Latest Edition Information</span></div><div>For the sixth edition (October 2020), the data file has been updated due to revisions made to the weighting methodology. Further information is available in the <span style="font-style: italic;">Improvements to the Weighting Methodology Used in the Labour Force Survey Longitudinal Datasets</span> document which has also been added.</div>

### 背景
《劳动力调查（Labour Force Survey, LFS）》是采用国际统一的就业、失业与经济不活动状态定义的独特信息来源，涵盖职业、培训、工作时长以及16岁及以上家庭成员个人特征等广泛相关主题，可用于支撑社会、经济与就业政策的制定。该调查于1973年至1983年首次以每两年一次的频率开展；1984年至1991年改为年度调查，包含全年持续开展的季度调查与春季季度的“补充”调查（此后数据按季度采集）。1992年起，该调查开始提供季度数据，季度样本量大致等同于此前的年度数据，自此该调查更名为《季度劳动力调查（Quarterly Labour Force Survey, QLFS）》。1994年12月起，北爱尔兰的数据采集转为完整季度周期，以与英国其他地区接轨，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）。更多关于QLFS的背景信息可参阅相关文档。

### 纵向数据
LFS会将每个样本家庭保留连续五个季度，每季度替换五分之一的样本。主调查旨在生成截面数据，但现已将每个个体的数据进行关联，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，含首尾时段），包含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，可例如提供不同劳动力市场类别（就业、失业与经济不活动）间随时间变化的总流动信息，以此展现在各类别间流动的人群细节。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，并与人口中的其他群体进行对比。不过，此类纵向数据关联操作可能引发方法论层面的问题，进而扭曲数据结果。英国国家统计局（Office for National Statistics, ONS）仍在对这些问题开展研究，并建议应审慎考量结果的呈现方式，必要时需在输出结果中附上警示说明。

### 新的重新加权政策
在新的重新加权政策发布后，ONS审查了2019年期间公布的最新人口估计数据，并决定不对2019年LFS与年度人口调查（Annual Population Survey, APS）开展重新加权工作。因此，下一次重新加权工作将于2020年进行，届时将纳入2019年地方人口预测数据（2020年5月发布）与2019年年中人口估计数据（2020年6月发布）。预计重新加权后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。

### LFS文档
档案馆可获取的伴随LFS数据集的文档，主要包含对应年度的用户指南手册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，因此建议用户在开始分析前，先在ONS的《劳动力调查——用户指南》页面查看最新文档。这一点对于老旧QLFS研究的用户尤为重要，因为用户指南文档中的信息与指引可能已随时间发生变化。

### 源自QLFS的额外数据
档案馆还留存有更多QLFS系列数据：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、为欧盟统计署（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。

### 变量DISEA与LNGLST
由于2017年4月至6月与2017年7月至9月间存在明显的数据不连续性，ONS暂停的A08数据集（残疾人劳动力市场状况）现已恢复可用。鉴于此次数据不连续性及现阶段调查结果尚不明确，在2017年4月至6月与后续时间段的数据间进行比较时应格外谨慎。同时用户需注意，该类估计未经过季节性调整，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月的估计数据时，针对该类估计的历史比较提供进一步建议。一篇阐述迄今为止已开展的质量保证调查的文章，可在ONS方法论网页查阅。若对A08数据集有任何疑问，请发送邮件至[e-mail]。

### 2021年与2022年数据文件的职业数据
ONS已发现其多项调查在2021年和2022年数据文件中存在部分职业数据采集问题。尽管其估计整体影响较小，但这将影响部分细分（四位标准职业分类（Standard Occupational Classification, SOC））职业的细分数据及其衍生数据的准确性。更多信息可参阅ONS于2023年7月11日发布的文章：《英国ONS劳动力调查中编码错误的职业数据修订：2021年1月至2022年9月》。

### 2022年加权
最新LFS估计所使用的人口总量，基于2021年的模式，采用英国、欧盟及非欧盟人口的实时信息（Real Time Information, RTI）数据的预测增长率。因此，LFS所使用的总人口未考虑2021年6月以来的移民、出生率、死亡率等变化，故而总量估计可能高估或低估真实数值，使用时应谨慎。不过，比率估计将保持稳健。

### 最新版本信息
第六版（2020年10月）因加权方法论的修订更新了数据文件。更多信息可参阅《劳动力调查纵向数据集加权方法的改进》文档，该文档也已同步添加。