Labour Force Survey Five-Quarter Longitudinal Dataset, June 1993 - August 1994

<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> For the second edition of the study, the depositor supplied a re-weighted version of the data file. The re-weighting has been done to bring LFS data in line with the population estimates from the 2001 Census.

<p><b>背景</b><br>
《劳动力调查（Labour Force Survey, LFS）》是采用国际通用的就业、失业及经济不活动状态定义，同时涵盖职业、培训、工作时长、16岁及以上家庭成员个人特征等广泛相关主题的独特信息来源，可为社会、经济与就业政策制定提供参考。该调查于1973年至1983年首次每两年开展一次；1984年至1991年转为年度调查，包含全年季度调查与春季季度补充调查（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，以匹配英国其他地区，自此QLFS覆盖全英国（英国数据档案馆仍留存有额外的北爱尔兰年度LFS数据集）。如需了解QLFS的更多背景信息，可参阅相关文档。<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。主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波次的数据，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）的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。通过关联记录构建纵向维度，可提供不同劳动力类别（就业、失业、经济不活动）间随时间变化的总流动信息，详细展示在各类别间流动的人群情况。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，并与人口中的其他群体进行对比。不过，此类纵向关联可能引发方法学问题，从而扭曲数据结果。英国国家统计局（Office for National Statistics, ONS）仍在对此类问题开展研究，并建议对结果的呈现需谨慎考量，必要时应在输出结果中附带相关警示。<br>
<br>
<b>LFS文档</b><br>
档案馆配套LFS数据集的文档，主要包含各年度对应问卷及最新版的用户指南手册。但英国国家统计局会定期更新手册内容，因此建议用户在开展分析前，先访问英国国家统计局的<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>页面查看最新文档。<b>这一点对于使用旧版QLFS研究的用户尤为重要，因为用户指南中的信息与指引可能已随时间发生变更。</b><br>
</p>
<p><span style="font-weight: bold;">2021年与2022年数据文件的职业数据</span><br>
</p>
<p>英国国家统计局发现，其多项调查在2021年和2022年的数据文件中存在部分职业数据采集问题。尽管评估认为整体影响较小，但这将影响部分细分（四位数字标准职业分类（Standard Occupational Classification, SOC））职业的细分数据准确性，以及基于此类数据衍生的统计结果。更多详细信息可参阅英国国家统计局2023年7月11日发布的文章：<a title="英国国家统计局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" href="https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/articles/revisionofmiscodedoccupationaldataintheonslabourforcesurveyuk/january2021toseptember2022" style="background-color: rgb(255, 255, 255);">英国国家统计局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>本次最新LFS估算所使用的人口总数，基于2021年的人口模式，采用来自英国、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，本次LFS使用的总人口数未考虑2021年6月以来移民、出生率、死亡率等方面的变化，故而水平估算值可能高估或低估真实数值，使用时需谨慎。不过，比率估算值仍将保持稳健。<br>
对于本研究的第二版，数据存档方提供了经重新加权的数据文件版本。本次重新加权旨在使LFS数据与2001年人口普查的人口估算结果保持一致。