Publishing Seasonally Adjusted Data

Anu PeltolaEconomic Statistics Section, UNECE

UNECE Workshop on Seasonal AdjustmentUNECE Workshop on Seasonal Adjustment20 – 23 February 2012, Ankara, Turkey

February 2012 UNECE Statistical Division Slide 2

Overview

Presentation of growth rates Detecting turning points Statistical news releases Improving readability Extracts from statistical news Availability of time series data General recommendations for new releases

– example for industrial production User support

February 2012 UNECE Statistical Division Slide 3

Presentation of Growth Rates

Without seasonal adjustment Growth rate from the same period of the previous year,

e.g. January 2012 to January 2011 Not free from calendar effects & historical picture

Seasonal adjustment Makes different periods comparable Provides faster indications of changes

Choice of growth rates for statistical releases requires careful consideration

Use consistent terminology for growth rates

February 2012 UNECE Statistical Division Slide 4

Detecting Turning Points

February 2012 UNECE Statistical Division Slide 5

Re-designing Statistical News Releases

According to the ESS Guidelines on Seasonal Adjustment:

Analyze the results of seasonal adjustment before publishing data

Ensure transparency to users Assist users in making informed decisions Facilitate easy access to time series data Provide seasonally adjusted figures if

seasonality is present

February 2012 UNECE Statistical Division Slide 6

Challenges with Statistical Releases

Offer the relevant information in a concise form

Keep the message simple and understandable

Include comprehensive information for correct conclusions

Guidelines: Handbook on Data and Metadata Reporting and Presentation (OECD)

February 2012 UNECE Statistical Division Slide 7

Recommendations for Releasing Time Series Data

1. When seasonality is present offer seasonally adjusted2. Focus on adjusted - give access to the original 3.+4. At the minimum provide period-to-period growth

rates on seasonally adjusted5. Year-on-year changes based on raw data or calendar

adjusted8. Disseminate a non-technical explanation of seasonal

adjustment9. Provide information for assessment of reliability10. Provide metadata to enable repeating adjustment

February 2012 UNECE Statistical Division Slide 8

Content of Statistical Releases

When releasing data with seasonal influence• Recommended to include in the release:

Higher level aggregates + Main contributors to change Period-to-period growth rates for the latest period Year-on-year growth rate

(from calendar adjusted or original data) Main revisions to the previous release

• Additional options: Growth rates based on the three months sum or moving

average – useful with volatile series Change or the value in levels Cumulative growth rates

February 2012 UNECE Statistical Division Slide 9

Extracts from Statistical News – Sweden

Increase in industrial production in July

Industrial production increased by 2.8 percent in seasonally adjusted figures in July compared to June. Comparing July with the same month of the previous year, industrial production increased by 8.2 percent in working day adjusted figures.

The production in the industry sub-sectors…

... when comparing the latest three month period, May-July, with the previous three month period…

... development was the strongest in the electrical equipment industry…

The figures for July are preliminary. Since the previous publication the change in industrial production in June compared to May has been revised upwards by…

www.scb.se/Pages/PressRelease____320267.aspx

February 2012 UNECE Statistical Division Slide 10

Extracts from Statistical News – United Kingdom

www.ons.gov.uk/ons/dcp171778_233168.pdf

February 2012 UNECE Statistical Division Slide 11

Time Series Seasonally adjusted data are at their most

useful form in a time series format, provide:• Access to the complete series• Original and seasonally adjusted series in full length• Access to trend-cycle and calendar day adjusted

series• Index numbers, in a time series form, enable

comparison of different sectors of the economy or different regions or countries

• To provide only the latest growth rate without any time series is not useful enough!

February 2012 UNECE Statistical Division Slide 12

Remember the End-Point Problem

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Published 05/2008 Published 03/2009

February 2012 UNECE Statistical Division Slide 13

UNSD - Releasing Industrial Production Index

International Recommendations for the Index of Industrial Production (UNSD, 2010)• Data released as soon as possible noting the

trade-off between timeliness and quality• Follow an advance release calendar and

consistent release practices > policy!• Make data available to all users at the same time• Foster confidentiality of individual data• Provide contact details of relevant statisticians

February 2012 UNECE Statistical Division Slide 14

User support

Bases on• Transparency of metadata• Availability of general explanations on

the statistical methods applied and• Good design of statistical releases• Websites providing additional data

and metadata for those interested• Availability of experts in statistics

February 2012 UNECE Statistical Division Slide 15

Effective News Release

According to the UNECE Making Data Meaningful Guide:

Tells a story about the data Has relevance for the public Catches the reader's attention quickly with a

headline or image Is easily understood, interesting and often

entertaining Encourages others, including the media, to

use statistics appropriately to add impact to what they are communicating