UK LLC sample - an explanation#
Last modified: 30 Oct 2024
The UK LLC TRE contains data about >300,000 participants from 20 different LPS. We call this pooled sample the UK LLC sample. The UK LLC sample is complex and dynamic because:
Each LPS provides information to UK LLC on a sub-set of their participants.
The sample provided by each LPS will change as new participants join or some withdraw consent to be included in different linkages and/or the UK LLC as a whole.
New LPS may join UK LLC and some LPS may withdraw from UK LLC.
Changes to the UK LLC sample occur in a controlled manner every quarter when LPS are required to communicate any changes to their LPS sample.
Following updates to the UK LLC sample, UK LLC establishes a ‘data freeze’ which comprises a number of tables that summarise the broad characteristics of the UK LLC sample at that point in time. Each data freeze will be given a DOI and all data tables are retained to help track changes to the UK LLC sample and to promote reproducibility of analyses.
Data freezes are critical in helping researchers to understand the UK LLC sample that underpins the datasets at the point in time they are granted access to them.
At each quarterly data freeze the following tables are produced:
• Table 1 – Number of participants enrolled in each LPS and, of these, the number included in the UK LLC TRE
• Table 2 – Percentage of participants from each LPS in the UK LLC TRE with permission to link to their NHS England records and the % that are successfully linked, categorised according to their legal basis (section 251 or consent)
Please note: LPS can update or submit datasets at any time and if these occur between data freezes, the information presented in Tables 1 and 2 will not reflect these changes.