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Seasonal adjustment/ Single Analysis/ New

Seasonal adjustment/ Multiprocessing/ New

SAProcessing-xx/ Run

Save to the workspace

Seasonally adjust

• For second adjustment of the same data, decide your update strategy

• Current adjustment = fixed forecasts

• Concurrent adjustment = nothing fixed

Analyse and refine

Visual check

• Is the seasonal component lost in the irregular?

Visual check

• Check the S-I ratio for moving seasonality

Models applied

• Information about pre-processing:

• the estimation time span used,
• corrections for trading days and Easter,
• type of applied ARIMA model,
• the dates and types of outliers as well as
• the distribution of residuals

• Information about decomposition:

• the applied decomposition model,
• statistical indicators to validate the model

Quality Diagnostics

• Demetra+ offers a wide range of quality measures

• Verbal description also

• Basic checks = annual totals

• Residuals, i.e. the part of data not explained by modelling, should not include any information

Quality Diagnostics

• Is there some residual seasonality after adjustment?

Quality Diagnostics

• Are there large revisions – is the model stable?

Quality Diagnostics

• Do the residuals follow the normal distribution?

• Are they random?

Refine and adjust

• Seasonal adjustment is an iterative process

• After the first adjustment, you can try different specifications

• For example, from RSA 5 to RSA 4

• In multiprocessing, you can edit a single series by double clicking its name in the results

• You can maintain the previous adjustments for comparison

Document and publish

Document choices

• Document the first page of Main results, Pre-processing, Decomposition and Diagnostics

• Archive the resulting time series for later revision analysis

• Prepare metadata to be published to the users of statistics

• ESS metadata template
• OECD Data and Metadata Reporting and Presentation Handbook

Export data

• You can export to several kinds of outputs

• Main menu: SAProcessing-xx/Generate output
• Copy: TramoSeatsDoc-x/Copy/Results

Prepare publication

• Redesign the content of data releases when you start with seasonally adjusted data

• Consider how to explain revisions, and plan in advance how to revise these data

• The press releases should be simple

• Offer some more details on the web site, e.g. regional or industry level data

Support users

• Seasonal adjustment aims at better service for the users of statistics

• Define a clear framework / policy

• choice of method and software
• timing of reanalysis of parameters and models
• treatment of outliers
• practices with revision and dissemination

Why Seasonally Adjust and How? Approaches X-12-ARIMA, TRAMO/SEATS, X-13 A/S and Tools

• Anu Peltola Economic Statistics Section, UNECE

Overview

• What and why

• Basic concepts

• Methods

• Software

• Recommendations

• Useful references

A Coyote Moment Did We Notice the Turning Point?

Economic Crises – Statistics

• Did we give any warnings?

• A responsibility for the statistical offices? A new task?
• Important to all users of statistics
• Not only to politicians, but also to enterpreneurs and citizens
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