The Aqua Book: Guidance on producing quality analysis for government

Author HM Treasury

The HM Treasury’s Aqua Book is essential reading for local authorities, and other relevant place-stakeholders, applying for funding and forming business cases. It focuses on analysis and the use of evidence in decision-making, which is important for successful policy development, appraising options, and measuring performance. Used alongside complementary resources, such as the Magenta Book and Green Book, it helps with the development of transparent, objective, evidence-based appraisal, evaluation, and formation of proposals, to inform decision making.

Date added 26 October 2020
Last updated 26 October 2020

The HM Treasury’s Aqua Book is essential reading for local authorities, and other relevant place-stakeholders, applying for funding and forming business cases. It focuses on analysis and the use of evidence in decision-making, which is important for successful policy development, appraising options, and measuring performance. It sets out the following key principles of ‘analytical quality assurance’ to support effective analysis (p.6):

  • Proportionality of response - extent of the analytical quality assurance effort should be proportionate to the risks associated with the intended use of the analysis.
  • Assurance throughout development - quality assurance considerations should be taken into account throughout the life cycle of the analysis and not just at the end.
  • Verification and validation - analytical quality assurance is more than checking that the analysis is error-free; it must also include if the analysis is fit for purpose.
  • Analysis with RIGOUR - quality analysis needs to be repeatable, independent, grounded in reality, objective, have understood and managed uncertainty, and the results should address the initial question robustly.

The Aqua book is split into three parts, and includes topics such as decision-making and analysis; commissioning analysis; quality assurance; taking into account uncertainty within analysis; verification and validation; and analytical assurance. Used alongside complementary resources, such as the Green Book, Magenta Book, and Managing Public Money Guide, it helps to inform decision making and the development of sound, evidence-based business cases.