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Vol. 7, No. 6 • July 2012­­

DALLASFED

Economic
Letter
Real-Time Historical Dataset Enhances
Accuracy of Economic Analyses
by Adriana Z. Fernandez, Evan F. Koenig and Alex Nikolsko-Rzhevskyy

} A growing body
of empirical
macroeconomic
literature suggests
that analyses using
real-time data often
yield substantially
different—and more
accurate—conclusions.

R

evised U.S. gross domestic
product (GDP) growth numbers released in summer 2011
revealed that the national economy was in worse shape two years after
the recession ended than earlier data had
suggested and that the downturn itself
had been deeper than previously estimated. Revisions such as these from government agencies are commonly issued
to account for errors, data updates and
measurement changes. Such adjustments
involve important economic variables
and affect not only the latest available
statistic, but also the historical properties of an entire data series. That means
revisions can be far-reaching, affecting
structural model results, forecasts and
monetary policy.
When data are subject to change, realtime data—the information available to
researchers and policymakers at the time
they conducted their analyses—rather
than the most up-to-date figures are necessary to appropriately assess a particular
economic model or forecast or understand
a given monetary policy action. A growing body of empirical macroeconomic
literature suggests that analyses using
real-time data often yield substantially different—and more accurate—conclusions
than those relying on the final revisions.1

However, such research remains limited,
largely reflecting the difficulties of compiling real-time data and the technical complexity of using “vintages,” or snapshots of
data at points in time.
Economists Dean Croushore and Tom
Stark published their large Real-Time
Data Set for Macroeconomists (RTDSM)
roughly a decade ago, with snapshots of
the U.S. economy starting in 1965. Their
work established the importance of realtime data and became the U.S. dataset for
forecasters and others engaged in research
affected by data revisions. Yet very little
work has been done to collect and analyze such figures for economies outside
the U.S.—even as globalization has made
real-time international data increasingly
relevant. The Original Release Data and
Revisions Database (ORDRD) from the
Organization for Economic Cooperation
and Development (OECD) is the most
comprehensive and well-maintained
international real-time database. Updated
monthly, it provides vintages of monthly
and quarterly data for member countries
beginning in January 1999.2 Its drawback:
It covers only the past decade, even though
the OECD’s recorded figures go back to the
organization’s inception in 1961.
Seeing the value in extending the
dataset, Federal Reserve Bank of Dallas

Economic Letter

Chart

1

U.S. Real GDP Undergoes Major Revision in Summer 2011

Real GDP (billions of dollars)

13,500
13,400
13,300
13,200
Data available in ’11:Q2

13,100
13,000
12,900
12,800

Four Important Applications

12,700
12,600
07:Q2

Data available in ’11:Q3
07:Q4

08:Q2

08:Q4

09:Q2

09:Q4

10:Q2

10:Q4

11:Q2

SOURCE: Real-Time Data Set for Macroeconomists, www.philadelphiafed.org/research-and-data/real-time-center.

researchers took on the task of compiling
a comprehensive quarterly dataset of 13
variables for each of the 26 OECD countries
for which sufficient data were available,
drawing from hard copies of historical
documents and the OECD Main Economic
Indicators from 1962 through 1998. The
result of that work, the Real-Time Historical
Dataset for the OECD (RTHD-OECD), is a
complementary real-time dataset that can
be easily merged into the existing OECD
real-time dataset.3 A current version of
RTHD-OECD can be downloaded at www.
dallasfed.org/institute/oecd/index.cfm.
(While our dataset went through many
checks to ensure quality, minor errors may
still exist. Therefore, a preliminary release
has been made available for comment at
www.rthd-oecd.org.)

Working with ‘Vintages’
The downward revision to real GDP
in the U.S. in summer 2011 revealed that
the pace of inflation-adjusted economic
growth had substantially decreased during the second quarter. Revisions to prior
quarters showed real output in the 2007–09
recession fell much more than initially estimated (Chart 1). The chart demonstrates
how the picture can change when new
vintages of data are used.
If we move a few vintages back, the
U.S. real GDP real-time data series would
resemble the matrix in Table 1, where

2

ficient) for at least one of the four variables
considered (Table 2).7
The positive readings in virtually all
significant revisions suggest that statistical
agencies may have a tendency to underestimate inflation and growth in real GNP/
GDP, the price level, industrial production
and money supply in their earlier estimates.
Looking at the overall dimension of corrections, the absolute value of mean revision
analysis (Chart 2) suggests that in international research, corrections are simply too
large to be ignored—as traditional reviseddata research does.

each successive column characterizes
the snapshot of quarterly data containing
the information available at that vintage
date.4 Third quarter 2011 revisions reveal a
slower economy not only in second quarter 2011 but dating back to the beginning
of the recession. Traditional revised-data
research would use only the last column of
data—or the latest available information—
ignoring previous revisions.
An important aspect of real-time
research is analysis of revisions. Generally,
when governments make efficient use of all
available information, revisions add “news”
and are not predictable between vintages.
When they don’t, revisions merely reduce
“noise” and are inefficient, and later values
may be predicted.5
The RTHD-OECD presents the opportunity to assess efficiency in a longervintage span than previous real-time data
allowed. Categorizing revisions by the lag
length (in quarters) with which they are
released, we look for recognizable patterns
that would provide evidence against efficiency—specifically whether revisions are
significantly positive or negative over the
whole historical period.6
At a minimum, efficiency requires that
revisions to a series should be zero on
average. Accordingly, we check whether
revisions differ significantly from zero. The
results show that in 16 of 26 countries,
revisions seem to be predictable (i.e., inef-

The RTHD-OECD may be used in
many areas of international macroeconomic research in which data revisions
matter. Four important applications illustrate the potential of the dataset—which,
when merged with ORDRD, provides
coverage from first quarter 1962 to second
quarter 2010: 8
1. Testing some of the most frequently
used output-gap estimation techniques.
The output gap, a key statistic in many
important macroeconomic models, shows
the difference between an economy’s
potential and current output.9 By assessing
output-gap estimation methods, researchers
and policymakers can identify those generating the most accurate signals.
2. Assessing the predictive ability of the
output gap. The output gap is often used as
an indicator of future inflation, based on the
empirically observed relationship between
the two variables (initially identified by
economist A.W. Phillips and known as the
“Phillips curve”).10 Using the combined
dataset, we find that the additional predictive power of the output gap is minimal or
nonexistent in real time.
3. More accurately gauging the effect of
inflation when interpreting data revisions. In
most theoretical models, inflation is thought
to have a significant, but temporary, impact
on the economy. With the dataset, we
find that by making accounting more difficult, higher inflation amplifies the causes
and extent of data revisions, which could
increase the likelihood of policy mistakes.11
4. Spotting vulnerabilities in nominal
exchange-rate forecasting models. Most
of these models are developed and tested

Economic Letter • Federal Reserve Bank of Dallas • July 2012

Economic Letter

Table

1

Period
2007:Q3
2007:Q4
2008:Q1
2008:Q2
2008:Q3
2008:Q4
2009:Q1
2009:Q2
2009:Q3
2009:Q4
2010:Q1
2010:Q2
2010:Q3
2010:Q4
2011:Q1
2011:Q2

How U.S. GDP Data Change During Successive Revisions
09:Q2
11,625.70
11,620.70
11,646.00
11,727.40
11,712.40
11,522.10
11,340.90
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.

09:Q3
13,321.10
13,391.20
13,366.90
13,415.30
13,324.60
13,141.90
12,925.40
12,892.40
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.

Vintages (billions of dollars)
10:Q1
10:Q2
10:Q3
13,321.10
13,321.10
13,268.50
13,391.20
13,391.20
13,363.50
13,366.90
13,366.90
13,339.20
13,415.30
13,415.30
13,359.00
13,324.60
13,324.60
13,223.50
13,141.90
13,141.90
12,993.70
12,925.40
12,925.40
12,832.60
12,901.50
12,901.50
12,810.00
12,973.00
12,973.00
12,860.80
13,155.00
13,149.50
13,019.00
n.a.
13,254.70
13,138.80
n.a.
n.a.
13,216.50
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.

09:Q4
13,321.10
13,391.20
13,366.90
13,415.30
13,324.60
13,141.90
12,925.40
12,901.50
13,014.00
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.

10:Q4
13,268.50
13,363.50
13,339.20
13,359.00
13,223.50
12,993.70
12,832.60
12,810.00
12,860.80
13,019.00
13,138.80
13,194.90
13,260.70
n.a.
n.a.
n.a.

11:Q1
13,268.50
13,363.50
13,339.20
13,359.00
13,223.50
12,993.70
12,832.60
12,810.00
12,860.80
13,019.00
13,138.80
13,194.90
13,278.50
13,382.60
n.a.
n.a.

11:Q2
13,268.50
13,363.50
13,339.20
13,359.00
13,223.50
12,993.70
12,832.60
12,810.00
12,860.80
13,019.00
13,138.80
13,194.90
13,278.50
13,380.70
13,438.80
n.a.

11:Q3
13,269.80
13,326.00
13,266.80
13,310.50
13,186.90
12,883.50
12,663.20
12,641.30
12,694.50
12,813.50
12,937.70
13,058.50
13,139.60
13,216.10
13,227.90
13,270.10

SOURCE: Real-Time Data Set for Macroeconomists at www.philadelphiafed.org/research-and-data/real-time-center.

Table

2

Significant Average Revisions Denoting ‘Inefficient’ Revisions

1
U.S.
Australia
Austria
Canada
Denmark
Finland
Germany
Greece
Italy
Japan
Mexico
Netherlands
Norway
Portugal
Switzerland
Turkey

Real GNP/GDP
Release lag
2
3
0.47**

4

1
0.12**

Price level
Release lag
2
3

–0.30**

4

0.28* –0.29**

0.28*

Industrial production
Release lag
1
2
3
0.28**
–0.19*
–0.85*
–0.34**

4

1

Money supply
Release lag
2
3
–0.27*

0.22*
–0.41*

0.33*
0.30**
0.86*

–1.17*
–0.31*

0.19*
–0.16*

0.50*
–1.40*

4

0.24*

0.23**
2.21**
0.42**

0.32*
1.62**

5.63**

0.52*
–0.48*
1.18**
2.86**

0.29**
1.97**

2.23**

NOTES: All variables are expressed in terms of annualized quarter-over-quarter growth rates. Significance at 5 and 10 percent is denoted with * and **, respectively. Real gross national product
(GNP) is used when real gross domestic product (GDP) is unavailable.
SOURCE: Authors’ calculations.

using revised data.12 Our real-time analysis
adds evidence suggesting that revised data
analysis may result in misleading conclusions. A particularly interesting case is the
British pound, whose exchange rate is predictable at the short horizon with revised
data but not with real-time data.

Importance of Real-Time Data

patterns in data. Given increased globalization and the advantages of using real-time
data, international researchers may want
to rethink the practice of using revised data
because of the potential for misleading
conclusions. The RTHD-OECD can serve
as a standard for forecasters and others
engaged in international research who
confront data revisions.

A growing body of empirical macroeconomic literature supports the importance
of real-time data analysis. Making use
of more-efficient real-time information,
researchers can more easily separate news
from noise and more accurately detect

Fernandez is an economist in the Houston
Branch and Koenig is a vice president and policy advisor in the Dallas office of the Federal
Reserve Bank of Dallas. Nikolsko-Rzhevskyy
is an assistant professor of economics at the
University of Memphis.

Notes
See “A Real-Time Data Set for Macroeconomists,” by Dean
Croushore and Tom Stark, Journal of Econometrics, vol. 105,
no. 1, 2001, pp. 111–30; “Monetary Policy Rules Based
on Real-Time Data,” by Athanasios Orphanides, American
Economic Review, vol. 91, no. 4, 2001, pp. 964–85; “Is the
Markup a Useful Real-Time Predictor of Inflation?” by Evan
Koenig, Economics Letters, vol. 80, no. 2, 2003, pp. 261–67;
and “Taylor Rules and Real-Time Data: A Tale of Two Countries and One Exchange Rate,” by Tanya Molodtsova, Alex
Nikolsko-Rzhevskyy and David H. Papell, Journal of Monetary
Economics, vol. 55, Supplement, 2008, pp. S63–79.
2
The official OECD Original Release Data and Revisions
Database is publicly available at http://stats.oecd.org/mei.
3
The OECD General Statistics Bulletin was replaced after
1964 by the OECD Main Economic Indicators. See
1

Economic Letter • Federal Reserve Bank of Dallas • July 2012

3

Economic Letter

Chart

2

Data Revisions Matter Globally
Absolute Mean Revisions for Real GNP/GDP Too Large to Ignore

Percentage points
14
12

One-quarter lag

Three-quarter lag

Two-quarter lag

Four-quarter lag

10
8
6
4
2

Turkey

U.K.
U.K.

Swittzerland

Turkey

Spain

Sweden

Norway

Portugal

New Zealand

Mexico

Netherlands

Korea

Luxembourg

Italy

n.a. n.a.
Japan

Ireland

Greece

France

Germany

Finland

Canada

Denmark

Austria

Belgium

U.S.

Australia

Iceland

n.a. n.a. n.a.

0

Absolute Mean Revisions for Industrial Production Appear Substantial
Percentage points
4
3.5

One-quarter lag

Three-quarter lag

Two-quarter lag

Four-quarter lag

3
2.5
2
1.5
1
.5

Swittzerland

Spain

Sweden

Portugal

Norway

New Zealand

Mexico

Netherlands

Korea

Luxembourg

Japan

Italy

n.a.
Ireland

Greece

Iceland

Germany

France

n.a.
Finland

Canada

Austria

Belgium

U.S.

Australia

Denmark

n.a.

0

NOTES: Revisions are defined as the difference in the value of a given variable in subsequent vintages. “Absolute mean
revision” refers to the total magnitude of changes; that is, adding changes whether they’re positive or negative. All variables are expressed in terms of annualized quarter-over-quarter growth rates. Real gross national product (GNP) is used
when real gross domestic product (GDP) is unavailable.
SOURCE: Authors’ calculations.

DALLASFED

Economic Letter

is published by the Federal Reserve Bank of Dallas. The
views expressed are those of the authors and should not
be attributed to the Federal Reserve Bank of Dallas or the
Federal Reserve System.
Articles may be reprinted on the condition that the
source is credited and a copy is provided to the Research
Department of the Federal Reserve Bank of Dallas.
Economic Letter is available free of charge by writing
the Public Affairs Department, Federal Reserve Bank of
Dallas, P.O. Box 655906, Dallas, TX 75265-5906; by fax
at 214-922-5268; or by telephone at 214-922-5254. This
publication is available on the Dallas Fed website,
www.dallasfed.org.

www.rthd-oecd.org for the list of countries and variables used
in the RTHD-OECD dataset.
4
Note that real GDP data are released with one quarter lag,
which implies that the last data point contained in each
vintage corresponds to the previous quarter’s real output.
5
Revisions are not predictable when all the available information is incorporated because, in that case, the error term is
independent and identically distributed. See “Risk and Return: Consumption Beta Versus Market Beta,” by N. Gregory
Mankiw and Matthew D. Shapiro, The Review of Economics
and Statistics, vol. 68, no. 3, 1986, pp. 452–59.
6
In our dataset, we found revisions released with one through
six lags. For this analysis, we present only the results for
one- through four-quarter-release lags.
7
For details on estimation and data employed in subsequent
tables and charts, refer to “A Real-Time Historical Database
for the OECD,” by Adriana Z. Fernandez, Evan F. Koenig and
Alex Nikolsko-Rzhevskyy, Federal Reserve Bank of Dallas
Globalization and Monetary Policy Institute, Working Paper
no. 96, December 2011.
8
For the empirical applications, we include only the G-7
economies. For details on estimation and data, see note 7.
9
Potential output refers to the output an economy would
produce if all its resources were fully employed.
10
For the analysis, we follow “The Reliability of Inflation
Forecasts Based on Output Gap Estimates in Real Time,”
by Athanasios Orphanides and Simon van Norden, Journal
of Money, Credit and Banking, vol. 37, no. 3, 2005, pp.
583–601.
11
The case is particularly clear in real GNP/GDP, where we
obtained results showing that a 10 percent increase in a
country’s inflation rate in a given year would increase growthrate revisions by a full 1 percent over the following year.
12
See “The Out-of-Sample Failure of Empirical Exchange
Rate Models: Sampling Error or Misspecification?” by Richard Meese and Kenneth Rogoff in Exchange Rates and International Macroeconomics, Jacob A. Frenkel, ed., Chicago:
University of Chicago Press, 2003, pp. 67–112; “Exchange
Rates and Fundamentals: Evidence on Long-Horizon Predictability,” by Nelson C. Mark, American Economic Review, vol.
85, no. 1, 1995, pp. 201–18; and “Out-of-Sample Exchange
Rate Predictability with Taylor Rule Fundamentals,” by Tanya
Molodtsova and David H. Papell, Journal of International
Economics, vol. 77, no. 2, 2009, pp. 167–80.

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