1. Euro-indicators Working Group
Luxembourg, 4th & 5th December 2008
Eurostat – Unit D1 Key indicators for the European policies

2. Some Principles for a Revisions Policy
Item 8.2 of the Agenda
Some Principles for a Revisions Policy
By Gian Luigi Mazzi and Rosa Ruggeri Cannata
Doc 242/08
Eurostat – Unit D1 Key indicators for the European policies

3. Outline Introduction Some Principles for a common revisions policy
Issues related to common revisions policy at domain level
Conclusions
Eurostat – Unit D1 Key indicators for the European policies

4. Introduction
Common revisions policy as an essential step for the harmonisation of revisions practices within the ESS
2007: joint Eurostat-OECD task force on Performing Revisions Analysis for Sub-Annual Economic Statistics
first attempt to define a general revisions policy focusing on PEEIs
Eurostat: internal discussion ongoing
Eurostat – Unit D1 Key indicators for the European policies

5. Eurostat – Unit D1 Key indicators for the European policies

6. Eurostat – Unit D1 Key indicators for the European policies

7. Eurostat – Unit D1 Key indicators for the European policies

8. Issues related to common revisions policy at domain level (1)
Routine revisions
Concurrent adjustment
Current adjustment
Mixture of the two strategies
Choice based on:
Presence of a bias in the first data release
Randomness of the revisions process
Degree of volatility of the indicator
Eurostat – Unit D1 Key indicators for the European policies

9. Issues related to common revisions policy at domain level (2)
Threshold
+ Avoid unnecessary revisions
+ Reduce the number of revisions
- Small but significant revisions could be discarded
Affects aggregation constraints
Threshold Level should depend on the characteristics of the generating process
Eurostat – Unit D1 Key indicators for the European policies

10. Issues related to common revisions policy at domain level (3)
Extent back in time: largely varying, from few ones to the whole series
routine revisions should involve a limited number of periods
annual ones a larger number
Avoid inconsistencies over the time as well as breaks
Revise the whole series within a multi-annual benchmarking or rebasing exercise at regular intervals
Users should be informed on the extent of different kind of revisions
Eurostat – Unit D1 Key indicators for the European policies

11. Issues related to common revisions policy at domain level (4)
Infra-annual time series: revisions policy of seasonally adjusted data
Specific issues of the generating process to be considered at domain level
ESS guidelines on seasonal adjustment
Revisions of raw data
Concurrent adjustment, partial concurrent adjustment, Current adjustment, controlled current adjustment
Eurostat – Unit D1 Key indicators for the European policies

12. Conclusions The Working Group is required to:
Express its opinion on the structure and contents of revision principles constituting the framework for the common revisions policy
Suggest comments and/or improvements to specific principles
Express its view on the treatment of specific statistical items
Report on already existing national revisions policies
Eurostat – Unit D1 Key indicators for the European policies

13. Thank you for your attention!
Eurostat – Unit D1 Key indicators for the European policies