DOI: 10.5255/ukda-sn-6676-18
title: Understanding Society: Waves 1-15, 2009-2024 and Harmonised BHPS: Waves 1-18, 1991-2009: Secure Access
title: Understanding Society: Waves 1- , 2008-: Controlled/Secure Access
title: United Kingdom Household Longitudinal Study; UKHLS

description: &lt;p&gt;&lt;span style="font-style: italic;"&gt;Understanding Society&lt;/span&gt; (UK Household Longitudinal Study), which began in 2009, is conducted by the Institute for Social and Economic Research (ISER) at the University of Essex, and the survey research organisations Verian Group (formerly Kantar Public) and NatCen. It builds on and incorporates the &lt;span style="font-style: italic;"&gt;British Household Panel Survey&lt;/span&gt; (BHPS), which began in 1991.&lt;/p&gt; 
&lt;p&gt;For full details of the main Understanding Society study, see SN 6614.&lt;/p&gt;
&lt;p&gt;The Understanding Society: Waves 1-14, 2009-2023 and Harmonised BHPS: Waves 1-18, 1991-2009: Secure Access dataset contains British National Grid postcode grid references (at 1m resolution) for the unit postcode of each household surveyed, derived from the ONS National Statistics Postcode Directory (ONSPD). Grid references are presented in terms of Eastings and Northings, which are distances in metres (east and north, respectively) from the origin (0,0), which lies to the west of the Scilly Isles. Each grid reference is given a positional quality indicator to denote the accuracy of the grid reference. In the majority of cases, the assigned grid reference relates to the building of the matched address closest to the postcode mean. The grid references provided for Northern Ireland postcodes use the Irish National Grid system that covers all of Ireland and is independent of the British National Grid. No grid references are provided for postcodes in the Channel Islands and the Isle of Man.&lt;/p&gt;
&lt;p&gt;The Secure Access version includes all files in the Special Licence version (see SN 6931 for full details), plus a file for each wave that contain 4 variables relating to the National Grid Reference for each household: easting, northing, positional quality indicator (w_osgrdind), and a variable identifying whether it relates to the British or Irish grid system. The Secure Access version also contains a data file with full dates of birth for Understanding Society and BHPS respondents which includes the day of birth variable which is only available in this study.&lt;/p&gt;
&lt;p&gt;&lt;b&gt;Related UK Data Archive studies:&lt;/b&gt;&lt;/p&gt;
&lt;p&gt;The Secure Access version of the dataset has more restrictive access conditions than standard End User Licence or Special Licence access datasets (see 'Access' section below). Further details and links to the less restrictive versions can be found on the Understanding Society series Key data page.&lt;/p&gt;
&lt;p&gt;&lt;b&gt;International Data Access Network (IDAN)&lt;/b&gt;&lt;/p&gt;
&lt;p&gt;These data are now available to researchers based outside the UK. Selected UKDS SecureLab/controlled datasets from the Institute for Social and Economic Research (ISER) and the Centre for Longitudinal Studies (CLS) have been made available under the International Data Access Network (IDAN) scheme, via a Safe Room access point at one of the UKDS IDAN partners. Prospective users should read the UKDS SecureLab application guide for non-ONS data for researchers outside of the UK via Safe Room Remote Desktop Access. Further details about the IDAN scheme can be found on the UKDS International Data Access Network webpage and on the IDAN website.&lt;/p&gt;
&lt;p&gt;&lt;b&gt;Latest edition information&lt;/b&gt;&lt;/p&gt;
&lt;p&gt;For the 18th edition (December 2025) Wave 15 data has been added. Other minor changes and corrections have also been made to Waves 1-14. Please refer to the revisions document for full details.&lt;/p&gt;
&lt;p&gt;&lt;b&gt;Suitable data analysis software&lt;/b&gt;&lt;/p&gt;
&lt;p&gt;These data are provided by the depositor in Stata format. Users are strongly advised to analyse them in Stata. Transfer to other formats may result in unforeseen issues. Stata SE or MP software is needed to analyse the larger files, which contain over 2,047 variables.&lt;/p&gt;
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