1. REVISIONS IN QUARTERLY GDP OF OECD COUNTRIES
MEETING OF THE WORKING PARTY ON NATIONAL ACCOUNTS Paris, October 2006
REVISIONS IN QUARTERLY GDP OF OECD COUNTRIES

2. Aims of the paper
Building, maintaining and using revisions databases: the QNA-MEI experience
Some remarks on strategy and tools for revisions analysis
Size of revisions to the first published estimates (P) on MEI (May 1995 – Aug 2005)

3. Main Results Revisions between three years later estimates (Y3) and the first published estimates (P) of q-o-q GDP growth rates (%) on MEI. Mean absolute revision ( )*
* BEL: 96.4;2002.4, DEU: , PRT: , KOR

4. Main Results Revisions between three years later estimates (Y3) and the first published estimates (P) of q-o-q GDP growth rates (%) on MEI. Relative mean absolute revision ( )*
* BEL: 96.4;2002.4, DEU: , PRT: , KOR

5. Main Results Comparison between previous year’s and this year’s updated results of revisions of the 3 years later published estimates to the first published estimates (Y3_P) of q-o-q GDP growth rates (%) on MEI. Mean absolute revision.
KOR: cannot be compared because last year data for Korea was not relevant.

6. The QNA-MEI revisions dataset
OECD-ONS workshop on “Assessing and improving statistical quality. Revision analysis for the national accounts”, 7-8 October 2004
“The OECD also agreed to explore the possibility to expand and maintain the revisions database that was set up for purposes discussed in the workshop.
An international dataset and the resulting summary measures of revisions should help to put countries’ individual revision analyses into an international context.”
First elements presented also at the STESEG meeting, June 2005

7. MEI as a revisions database source
MEI monthly snapshots in principle provide historical data on subsequent releases on a wide range of key variables
Provides a coherent set of variables representing the ‘information set’ available at successive monthly intervals
MEI has been published as a CD Rom for many years

8. OECD interest in a revisions database
Analysis – Are revisions random (i.e. centred around 0)? Are they in general becoming smaller?
Support internationally coordinated research work to improve the quality of early estimation methods
Encourage transparency in the statistical process

9. The QNA-MEI revisions dataset
Initial OECD work (Ahmad, Bournot & Koechlin, 2004) was for G7 countries, period 1996 – 2000
Current project (Di Fonzo, STESEG 2005)
Expand coverage to all OECD countries
Expand time period covered
Devise a scheme which can support ongoing production of real time database & summary revision analysis indicators
Quarterly GDP and its components

10. Data availability for GDP (constant prices, sa) in the QNA-MEI revisions database
MEI editions
Vintages
Countries
First
Last #
May-95
May-06
95q1
06q1
133
1: USA
94q4
05q4
13: AUS, CAN, CHE, DNK, ESP, FIN, FRA, GBR, ITA, JPN, NLD, NOR, NZL
Nov-95
95q2
127
1: DEU
Nov-96
95q4
115
1: PRT
Mar-97
96q3
111
1: BEL
Mar-00
99q3 75
1: KOR
Oct-03
03q2 32
1: CZE*
Nov-03 31
1: AUT*
Apr-04
03q4 26
1: GRC
Nov-04
04q2 19
1: IRL
Jul-05
05q1 11
1: HUN
Sep-00
00q2 65
2: SWE, TUR
00q1
1: MEX
Oct-05 8
1: SVK
---
3: ISL, LUX, POL

11. QNA-MEI revisions dataset Caveats for international comparisons
P are not necessarily flash estimates
Timeliness of P differs between countries
No attempt is made to isolate the different types of revisions, (including errors)
Differences may exist between estimates and national estimates
No investigation into influence of economic cycle
Period covers SNA93 introduction and other changes, fixed base, chain-linking

12. Release time of GDP (P) on MEI Further cautionary notes
MEI is commonly published during the first week of the month
Different release timing across countries
There is no guarantee that the first number published in MEI is really the first number ever released
‘QNA-MEI view’ on timeliness in the release of GDP
The true timeliness is ‘filtered’ through the publication practices adopted by OECD in the last decade

13. Revisions analysis: Summary statistics
Mean revision
Mean absolute revision
Mean squared revision
% L > P
% sign(L) = sign(P)

14. Elements for discussion
Presentation of revisions, evaluating the first revision registered on MEI, effect of different time periods on the summary statistics, stability of the results, use of other (simple) descriptive measures?
Possible use of a QNA-MEI revisions database by member countries?
Priority for analyzing other QNA series and how to use the results?
- e.g. as an input to internationally coordinated methodological work?
- To reconsider policies for communicating information on revisions to users?

15. THANK YOU!