Labour Force Survey Five-Quarter Longitudinal Dataset, April 1997 - June 1998

<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>
<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>
<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> This study was deposited in 2008, as a result of the move from seasonal to calendar quarters for the QLFS, and the reweighting process to 2007-2008 population figures. It combines data from previously-available QLFS seasonal five-quarter longitudinal datasets. The depositor has advised that small revisions to the data may have been made during this process, but they should not be significant.<br>
<br>

<p><b>背景</b><br>
<i>劳动力调查</i>（Labour Force Survey, LFS）是一套独特的信息来源，采用国际通用的就业、失业及经济非活跃状态定义，同时涵盖职业、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参考。LFS最初于1973年至1983年间以两年为周期开展。1984年至1991年期间，调查改为年度开展，包含全年实施的季度调查与春季季度的“补充”调查（当时数据按季度采集）。1992年起，调查可提供季度数据，季度样本量大致与此前年度样本量相当，该调查此后更名为<i>季度劳动力调查</i>（Quarterly Labour Force Survey, QLFS）。1994年12月起，北爱尔兰的数据采集改为完整的季度周期，以与英国其他地区保持一致，至此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）。如需了解QLFS背景的更多信息，可查阅相关文档。<br>
<br>
<b>纵向数据</b><br>
LFS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。该调查最初设计用于生成横截面数据，但目前已将每个个体的数据进行关联，以提供纵向信息。纵向数据包含两类关联数据集，均通过加权方法调整无回应偏差。两季度数据集关联连续两个调查波次的数据，而五季度数据集则关联一整年（例如2010年1月至2011年3月，含首尾时段）内的全部五个波次的数据。目前已生成可追溯至1992年冬季的完整纵向数据集序列。通过关联记录构建纵向维度，可获取不同劳动力群体（就业、失业及经济非活跃群体）间随时间变化的总流动情况，从而详细呈现于各类群体间流动的个体信息。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的个体后续活动与处境，并将其与人口中的其他群体进行对比。不过，这种纵向关联过程可能存在方法学问题，会导致数据失真。英国国家统计局（Office for National Statistics, ONS）仍在对这些问题开展研究，并建议需谨慎考量结果的呈现方式，必要时需在输出结果中附上相关警示。<br>
<br>
<b>LFS文档</b><br>
档案馆提供的LFS数据集配套文档，主要包含各卷用户指南的最新版本以及对应年度的适用调查问卷。不过，ONS会定期更新各卷文档，因此建议用户在开始分析前，先查阅ONS官网的<a href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/labourforcesurveyuserguidance" title="劳动力调查——用户指南" target="_blank">劳动力调查——用户指南</a>页面获取最新文档。<b>这一点对于使用早期QLFS数据集的用户尤为重要，因为用户指南文档中的信息与指南内容可能已随时间发生变更。</b><br>
</p><p><span style="font-weight: bold;">2021年与2022年数据集的职业数据</span><br>
</p><p>ONS已发现其多项调查在2021年与2022年数据集的部分职业数据采集过程中存在问题。尽管ONS评估整体影响较小，但该问题会影响部分细分（四位数字标准职业分类（Standard Occupational Classification, SOC））职业的分类数据及其衍生数据的准确性。更多信息可查阅ONS于2023年7月11日发布的文章：&nbsp;<a title="英国ONS劳动力调查2021年1月至2022年9月中编码错误的职业数据修订" 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2021年1月至2022年9月中编码错误的职业数据修订</a>。</p><p><span style="font-weight: bold;">2022年加权方案</span></p><p>最新LFS估算所用的人口总数，基于2021年的人口模式，采用来自实时信息（Real Time Information, RTI）数据的英国、欧盟及非欧盟人口预测增长率。因此，LFS所用的总人口数未考虑2021年6月以来移民、出生率、死亡率等因素的变化，由此得出的水平估算值可能高估或低估真实数值，需谨慎使用。不过，比率估算值仍保持稳健。</p><p>本数据集因QLFS从季度周期转为日历年季度周期，并重新加权至2007-2008年人口数据，于2008年入库存档。该数据集整合了此前已公开的QLFS季度五周期纵向数据集数据。存档方提示，在此过程中可能对数据进行了小幅修订，但该修订并不显著。<br>
<br>