Official Statistics

Valuation Office Agency revisions policy

Published 27 March 2017

1. Types of revision

1.1 Scheduled Revisions

These take place on receipt of subsequent updated information which is expected and are a part of the defined methodology for a particular statistical series. They might occur as part of the normal release practice for a given series where initial or provisional estimates are released and are always subsequently revised. For example, through benchmarking or rebasing exercises. Provisional releases will be marked as “provisional” and once these have been revised, the release will be marked as “revised”.

Key principles for handling of scheduled revisions:

• any official statistics outputs which are subject to scheduled revisions will contain a statement setting out how revisions will be handled. Revisions will be pre-announced in our statistical releases and on the VOA statistics page on GOV.UK
• for major revisions users will be consulted in advance so they understand the nature of the scheduled revision and its likely impact on the statistics. The revision will be explained again in the release itself when published
• in some cases, scheduled revisions will affect numbers that have been provided in Freedom of Information requests or Parliamentary Questions. Where this occurs a footnote will be included in the response

1.2 Non-scheduled revisions

Revision due to errors in statistical systems and processes

Occasionally, errors will occur in our statistical processes. The VOA takes precautions to minimise these errors and we continually review our processes and procedures to reduce this risk. In the rare case when errors do occur, we will thoroughly investigate how it occurred and strengthen our processes where necessary. A decision on whether to republish the figures will be made on a case by case basis by the Agency’s Lead Statistician.

Key principles for handling of revision of errors:

• any figures that have been revised or removed due to the original figures either being misleading or erroneous will be referenced in the footnotes. This will provide an explanation as to the nature and extent of the revision
• revisions will also be announced in the statistical release document

Changes in source systems or statistical methodology

Sometimes published series are subject to a one-off methodological change. This may happen when, for example, a source administrative system or a methodology is improved and changes to historical numbers are significant enough that a revision of previously released tables is needed. Where possible, we will consult with users on the changes and treat these as a change of methodology.

Key principles for handling of revision due to source systems or methodological change:

• the nature and reason for the change and the likely impact will be explained in the statistical release and accompanying documents. Footnotes will also be included in the statistical tables
• we will announce the date for the release of revised numbers or our intention to change the methodology in advance
• the revised numbers will be released according to the pre-announced date, in compliance with the same principles as the original information

2. For all revisions

Revisions will be assessed for disclosure risk before release, taking into account the possibility that some of the data in the revised output have already been released.

Revisions will also be assessed to balance the benefits (in terms of quality and accuracy) against the costs (including both costs to government and data suppliers), taking into account the expected uses of the statistics.

Revised publications will be clearly stated in the title, and where a revision to a figure is applied due to erroneous or misleading figures it will be denoted with an ‘r’ and a footnote to explain the reason for the revision. Should we decide not to implement a particular revision, this will be noted in the next issue of the relevant publication, together with the reason for this decision.

3. Valuation Office Agency’s Annual Report

Figures quoted in the VOA’s Annual Report may be revised as a result of non-scheduled revisions.

Mark Wardell is the Lead Statistician for the Valuation Office Agency.