Scottish Vacant and Derelict Land Survey: Revisions policy

This policy has been developed in accordance with the UK Statistics Authority Code of practice for Official Statistics (http://www.scotland.gov.uk/Topics/Statistics/About/NatStats) and the Scottish Government Revisions Policy (http://www.scotland.gov.uk/Topics/Statistics/About/CPSonRevisionsCorrections/).      

There are two types of revisions that this policy covers.

Scheduled Revisions:

Changes to the component data sources used in the statistical release will be incorporated in the next scheduled release. All figures which are expected to be revised will be clearly marked as provisional and an indication given of when revisions are expected to be published.  If possible an indication of the possible scale and nature of likely revisions will be given. On publication of revisions, all relevant releases will clearly indicate where a revision has occurred and the reasons why.

 In order to enable up to date information to be included, each annual return can be updated at any time after the initial publication of the figures for that year. Every year, as well as releasing figures for the latest year, we revise the previous six years to incorporate any data that came in shortly after the previous data collection period. Data prior to that will not be revised.

Local authorities return an annual snap shot of vacant and derelict sites. These are used to compile a consistent time series. The main reasons for revisions are:

• Local authorities may not update all historic site information every survey, consequently some site information may not be current. Changes to site details will be revised back to the time the change occurred (rather than when it was reported);
• Removal and addition of sites – the means by which new sites are detected are largely centred on the expert knowledge of local authority planning officers. Sites may not be known to a local authority in the year they become vacant or derelict and will be reported when the local authority becomes aware of them.
• Sites may be removed for definitional reasons, as work is undertaken to improve the quality of the data supplied. In this case the site is removed from the entire time series.

All other revisions to historic data (all data older than that currently due for revision) should only be made where there is a substantial revision, such as a change in methodology or definition.

 Non-scheduled Revisions

 If an error occurred as a result of the compilation, imputation or dissemination process, consideration will be given to:

• The importance of the statistic e.g. is it a headline figure or being used in significant ways?
• The size of the mistake particularly relative to any stated levels of accuracy
• The recipients of the mistake
• The consequences of the mistake – does it alter the main message of the statistics or any likely use?

Minor errors will be corrected in the next edition of the publication.  The correction will be made clear and reasons explained.

For substantial errors we will:

•   Correct the material on the website, making clear that this has been done.
•   Notify users of any substantial errors or errors which could affect their own work.
•   Where errors have been identified that will take time to correct advance notice should be given if possible with the expected release date and an indication of possible scale.

In the case of major corrections we will also issue a formal Statistical News Release subject to the normal procedures for such releases.

Communities Analytical Services

January 2012