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DATA PRESENTATION AND SEASONAL ADJUSTMENT

- SUMMARY OF WRITTEN COMMENTS -

DATA PRESENTATION AND SEASONAL ADJUSTMENT

- SUMMARY OF WRITTEN COMMENTS -

SHORT-TERM ECONOMIC STATISTICS EXPERT GROUP (STESEG)28 – 30 JUNE 2004

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• This is just a brief overview of comments. More in-depth discussion to be given in other presentations for this session:

Recommendation on terminology – Denis Ward (OECD)

Recommendations on growth rates – Robert Kirchner (Bundesbank)

Recommendations on seasonal adjustment –Bernard Lefrancois (Statistics Canada)

SUMMARY OF WRITTEN COMMENTSSUMMARY OF WRITTEN COMMENTS

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• Written comments on data presentation and seasonal adjustment received from 21 organisations – some very detailed

• Comments focused on:

terminology presentation of growth rates presentation of seasonally adjusted data

• Feedback on these three issues linked and also to be covered in the Manual

SUMMARY OF WRITTEN COMMENTSSUMMARY OF WRITTEN COMMENTS

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• There is general agreement on many of the recommendations, further elaboration on some and disagreement on relatively few (though key) recommendations

SUMMARY OF WRITTEN COMMENTSSUMMARY OF WRITTEN COMMENTS

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• Almost all agree on the central role of terminology and the need to provide clear standards for key data presentation concepts

• Some commented on the need to include clear definitions of concepts, especially growth rates in publications to inform users

• Some of the suggested definitions required rewording to make them clearer

• Where necessary insertion of formulae required to make them completely unambiguous

• Need also to publish guidelines in French to facilitate comparisons with current national practice / usage

TERMINOLOGYTERMINOLOGY

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Task Force Recommendations on Terminology

Agreement Modificatn required

Year-on-year growth rate

Annualised growth rate

Linear approximation of the annualised figure

Calendar or working day adjustment

Moving average

Preliminary / provisional

Cycle (in a time series)

Oscillation Delete term

Seasonal variation

Time series

Trend

Trend-cycle

Calendar effects component

Irregular component

Seasonally adjusted component or series

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• There was considerable discussion on the three task force recommendations on growth rates

• There was overall consensus to harmonise text and recommendations on growth rates with those on seasonal adjustment to remove inconsistencies in terminology and substance

• Some countries suggested merging of the two papers in the Manual

GROWTH RATESGROWTH RATES

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GROWTH RATESGROWTH RATES

Task force recommendation Agree Disagree

Rate of change with respect to previous period

Norway, South Africa, US BoC, Netherlands

Australia, US BLS

Rate of change with respect to same period of previous year

Norway, South Africa, Italy CB, NZ, Sweden, Netherlands

UK, ABS

Annualised growth rates Norway, US BoC, UK, NZ, Australia, Netherlands

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Main issues – underlying themes

For news releases what is general public interested in – SA data; trend cycle and irregular movements?

Does SA data reveal cyclical movements at turning points sooner than raw series or trend-cycle estimates?

What are merits of YoY based on SA v. raw or only TDA data?

What are the problems of using annualised growth rates – arising from seasonal patterns, trading day effects, irregular movements?

GROWTH RATESGROWTH RATES

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• There is considerable variation in national practices in the presentation of seasonally adjusted data (none/some/all)

• Some national agencies trying to work out corporate practices for SA, incl. rules for adjustment, length of time series, use of direct / indirect method

• One country emphasises trend-cycle data in key indicator publications – others currently evaluating use of T-C

• Most seemed to feel need for articulation of a set of presentation standards

• Though one country felt that this was perhaps premature given the current evolution of SA models and software

SEASONAL ADJUSTMENTSEASONAL ADJUSTMENT

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• Not all countries commented on each of the 12 recommendations individually

• There was general support for most of the recommendations proposed by the task force

• Though both the text and some recommendations require modification and / or elaboration + fix on editorial errors (Rs 7, 8, 12)

• Several countries commented on inconsistencies, especially with recommendations / text on growth rates

SEASONAL ADJUSTMENTSEASONAL ADJUSTMENT

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Task Force Recommendations on Seasonal Adjustment Over

all

Some None

1 SA when seasonality is present

2 SA series adjusted for trading day effects + other regular calendar variation

3 Series with no seasonal variation but with regular calendar variations referred to as calendar adjusted

4 Focus of press releases should be on SA series

5 SA series should be presented in their natural form, i.e. as levels

6 Press releases presenting SA flow series to provide p to p change in levels + growth rate

7 Annualised growth rates should not be used. Year over year growth rates preferable

8 Annualised or semi-annualised growth rates should be considered instead of year over year

9 Agencies should disseminate a non-technical explanation of SA and interpretation

10 Need to provide a minimum standard of information to assess reliability

11 Maintain metadata sufficient to enable outsiders to SA series

12 To present quarterly or monthly growth rates at annual rates annualised p to p growth rates should not be used

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Underlying issues / themes

• Need for expression advising users that a series has been adjusted for calendar effects

• Which series should be given emphasis – raw, TDA, SA, trend-cycle? One or several?

• Should sub-annual SA levels be annualised?

• What alternative presentation would satisfy user needs for a rate on an annual basis?

SEASONAL ADJUSTMENTSEASONAL ADJUSTMENT

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Underlying issues / themes (cont.)

• What type of annualised transformation of SA series in press release – period-to-period change; period-to-period growth rates; year-over-year growth rates; year-to-date totals?

• What metadata should be given out to general public and informed users to explain meaning of seasonal adjustment?

• How to measure validity of a seasonal adjustment measure? Reinvent wheel – pick up on work of other organisations, e.g. Eurostat.

SEASONAL ADJUSTMENTSEASONAL ADJUSTMENT

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Other issues

• Some countries mentioned other issues they would like to see covered in future, e.g. recommendations on:

Use of direct / indirect method of compilation

Role of trend-cycle estimates to identify underlying movement in time series – pros and cons

SEASONAL ADJUSTMENTSEASONAL ADJUSTMENT

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• Almost all agencies supported the preparation of the proposed Manual

• Saw need for harmonisation of contents of data descriptions as a prerequisite for data comparability.

• Particular support for glossary of key terms & recommendations on metadata

• Main proviso that OECD co-ordinates contents with related work by Eurostat to ensure consistency – especially on seasonal adjustment

• [Need to identify specific interfaces with Eurostat]

MANUALMANUAL

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Suggested changes

• Need a summary of recommendations with glossary of terms with links to further details

• Over elaboration on technical issues in some parts (e.g. 5.6.2) which may confuse and make users lose sight of key recommendations

• Could use links to more detail on technical detail

• Sections on growth rates and SA should be combined

• Translation into other languages – e.g. French (UN?)

MANUALMANUAL

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Suggested changes (cont.)

• Need to have stronger emphasis on presentation issues?

• More weight should be given to the needs of data users in the establishment of presentation standards?

• Corrections to text (e.g. stock/flow series definition)

• Inconsistent terminology (e.g. for working day effect, calendar effect, etc).

MANUALMANUAL

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Additional issues

• Are some suggestions for additional issues to be incorporated.

Linkage practices to maximise length of time series

Recommendations on need to have past data (100 years?) available in electronic format – sometimes electronic data only available for recent years

MANUALMANUAL

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Future work – Eurostat context

Draft Manual already incorporates material from:

STS / Structural Business Statistics Regulations Manuals on STS and SBS Eurostat publication “manual” – quite small Standard quality reports Work of seasonal adjustment and metadata groups on

CIRCA

• Other relevant sources will be discussed with Eurostat - suggestions?

SUMMARY OF WRITTEN COMMENTSSUMMARY OF WRITTEN COMMENTS

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Future work

SUMMARY OF WRITTEN COMMENTSSUMMARY OF WRITTEN COMMENTS

Data and Metadata Reporting and Presentation Manual

Data and Metadata Reporting and Presentation Manual

TerminologyTerminology Growth ratesGrowth ratesSeasonal adjustmentSeasonal adjustment