International Trade Statistics Expert Meeting,
September 2006, OECD Paris
International Export and
Import Price Indices Manual
Paul Schreyer, OECD
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A bit of history
1902: first industrial commodities price index in the USA for the
period 1867 – 1890
Method: un-weighted average of 250 commodities
Purpose: investigate effects of tariff laws on prices of
domestic and imported agricultural and manufactured
products
1903: first WPI for the UK presented by the Board of Trade,
and mainly derived from trade accounts
Method: 45 commodities
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100 years later: the Price Index Manuals

Efforts to address index methods concerns
– ISWGPS established in 1998;
– ILO, IMF, ECE, OECD, World Bank, Eurostat, and UNSD
– Core Group serving on ISWGPS
• ILO CPI Manual (2004) (first published 1989)
• IMF PPI Manual (2004) (first published 1979)
• IMF External trade XMPI Manual (draft) (first published 1981)
– Ongoing work:
• revised versions
• non-English translations
• Real estate price index (OECD)
• Core inflation (IMF)
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Organisation of the XMPI Manual
Foreword
Preface
Reader's guide
1. Introduction to XMPI methodology
2. Background, purpose, and uses of
export and import price indices
3. Valuation, timing, coverage, and
classifications
4. Data sources
5. Sampling issues in price collection
6. Price collection
7. Treatment of quality change
8. Item substitution, sample space, and
new goods
9. An overview of export and import
price index calculation
10. The treatment of specific products
11. Errors and bias in the export and
import price indices
12. Organization and management
13. Publication, dissemination, and user
relations
14. The system of price statistics
15. Index number theory
16. Axiomatic and stochastic approach
17. Economic approach
18. Transfer prices
19. Price indices using an artificial data
set
20. Elementary indices
21. Quality change and hedonics
22. Treatment of seasonal products
Glossary
Bibliography
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Organisation of the XMPI Manual
Foreword
Preface
Reader's guide
1. Introduction to XMPI methodology
2. Background, purpose, and uses of
export and import price indices
3. Valuation, timing, coverage, and
classifications
4. Data sources
5. Sampling issues in price collection
6. Price collection
7. Treatment of quality change
8. Item substitution, sample space, and
new goods
9. An overview of export and import
price index calculation
10. The treatment of specific products
11. Errors and bias in the export and
import price indices
12. Organization and management
13. Publication, dissemination, and user
relations
Background
14. The system of price statistics
15. Index number theory
16. Axiomatic and stochastic approach
17. Economic approach
18. Transfer prices
19. Price indices using an artificial data
set
20. Elementary indices
21. Quality change and hedonics
22. Treatment of seasonal products
Glossary
Bibliography
5
Organisation of the XMPI Manual
Foreword
Practice of
Preface
Reader's guide
compilation
1. Introduction to XMPI methodology
2. Background, purpose, and uses of
export and import price indices
3. Valuation, timing, coverage, and
classifications
4. Data sources
5. Sampling issues in price collection
6. Price collection
7. Treatment of quality change
8. Item substitution, sample space, and
new goods
9. An overview of export and import
price index calculation
10. The treatment of specific products
11. Errors and bias in the export and
import price indices
12. Organization and management
13. Publication, dissemination, and user
relations
14. The system of price statistics
15. Index number theory
16. Axiomatic and stochastic approach
17. Economic approach
18. Transfer prices
19. Price indices using an artificial data
set
20. Elementary indices
Practice
of and hedonics
21. Quality
change
22. Treatment
of seasonal products
compilation
Glossary
Bibliography
6
Organisation of the XMPI Manual
Foreword
Preface
Reader's guide
1. Introduction to XMPI methodology
2. Background, purpose, and uses of
export and import price indices
3. Valuation, timing, coverage, and
classifications Theoretical
4. Data sources aspects
5. Sampling issues in price collection
6. Price collection
7. Treatment of quality change
8. Item substitution, sample space, and
new goods
9. An overview of export and import
price index calculation
10. The treatment of specific products
11. Errors and bias in the export and
import price indices
12. Organization and management
13. Publication, dissemination, and user
relations
14. The system of price statistics
15. Index number theory
16. Axiomatic and stochastic approach
17. Economic approach
18. Transfer prices
19. Price indices using an artificial data
set
20. Elementary indices
21. Quality change and hedonics
22. Treatment of seasonal products
Glossary
Bibliography
7
Main issues associated with XMPI
Unit values rather than survey-based methods



Typically, even most detailed HS category brings together too
heterogenous products to use unit values as prices
XMPI Manual recommends survey-based price indices, based on
observations of fully described and differentiated products
Relevant methods are described in the XMPI Manual
Index number formulae


Like with other price indices, Laspeyres-type index numbers no more
correspond to target price indices
The Manual sets out the economic and index number theoretical reasons
for the choice of the target formula
Quality change and new goods

Common problem in all price indices (CPIs, PPIs) that equally affects
XMPI
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Main issues associated with XMPI
Treatment of seasonal commodities


For short-term indicators, the use of annual weights is problematic
when it comes to seasonal commodities: monthly price changes that are
out of seasons can be greatly magnified by annual weights
Special approaches to weighting needed for seasonal commodities
Insufficient or no coverage of services


While common to many price statistics, this seems to be particularly
acute in the area of XMPI with their traditional and strong focus on
products
XMPIs should however benefit from strong efforts by OECD countries
to develop producer price indices for services
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Drafting and review process


Based on and consistent with PPI Manual (2004), which in turn is
based on, and consistent with, CPI Manual (2004).
Working under the IWGPS:
– IMF drafted first version now on IMF web site;
– IMF wrote to statistical authorities asking for comments to be
posted;
– IMF organizing seminar in September, 2006 involving focus
group of countries, specialists and interested parties;
– Comments from above to be incorporated into draft and some
further specialist review;
– Refer back to IWGPI.
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Where to find manuals on the website
CPI Manual on ILO website:
www.ilo.org/public/english/bureau/stat/guides/cpi/index.htm
PPI Manual on IMF website:
www.imf.org/external/np/sta/tegppi/index.htm
XMPI (Draft) Manual on IMF website
www.imf.org/external/np/sta/tegeipi/
COMMENTS – IN PARTICULAR FROM TRADE
STATISTICIANS – MOST WELCOME!
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