The UK Data Service has been listed as a key resource for government evaluators in the latest version of the UK Government’s Magenta Book. Published by HM Treasury, the Magenta Book is the central guidance document on how to evaluate policies, programmes and projects.
The Magenta Book
The Magenta Book is intended to show policy teams, analysts and commissioners across central government what good evaluation looks like. Used alongside the Green Book, it aims to empower staff “to deliver better evidence, better decisions, and ultimately better outcomes for the public”.
The latest version, updated in May 2026, includes new guidance on assessing value for money, “test and learn” approaches to policy design, the responsible use of artificial intelligence in evaluation, and other key topics. It also features detailed advice on accessing, evaluating, using and linking data.
The UK Data Service
The new guidance identifies the UK Data Service as a vital source of data for government evaluators. It also states there “should be a presumption from the outset that all survey data should be archived, if possible, commonly through the UK Data Service.”
As Eve Little explains in an accompanying blog piece on our Data Impact blog, this “positions the UK Data Service as the expected home for survey data collected through government evaluation – reflecting a role that the UK Data Service has long played, and that the updated guidance now makes explicit.”
It also underscores the role data available through the UK Data Service continues to play in policymaking. You can learn more about these contributions at the Data Impact blog and via case studies and impact themes produced by the UK Data Service Impact Team.