Results, particularly for the latest Index of Services (IOS) quarter, are provisional and subject to revision as more up to date information becomes available. It is normal practice for IOS estimates to be revised.
Revisions to IOS estimates
These revisions will occur primarily in light of:
- late responses to surveys and administrative sources
- where cross survey congruence checks provide more accurate data - for example, data can be revised back for up to four quarters and finalised once comparisons have been made with the current year Annual Business Inquiry (ABI) returns
- where there are revisions to seasonal adjustment factors which are re-estimated every quarter
Very few statistical revisions arise as a result of ‘errors’ in the popular sense of the word. All estimates, by definition, are subject to statistical ‘error’ but in this context the word refers to the uncertainty inherent in any process or calculation that uses sampling, estimation or modelling.
Most revisions reflect either the adoption of new statistical techniques, or the incorporation of new information, which allows the statistical error of previous statements to be reduced. Only rarely are there avoidable ‘errors’ such as human or system failures, and such mistakes are made quite clear when they do occur.
Quality and revisions
A detailed Index of Services revisions policy which outlines the treatment of planned and unplanned revisions and quality report are available.