In this paper, we present a real-time macro data set for the UK. Each variable has many different vintages---reflecting the revisions that occur in real time. Our aim is to provide a resource that allows researchers to assess the robustness of their results to data revisions. We illustrate the importance of this issue by analysing the impact of real-time data on UK inflation forecasts.

Andreas Pick

Egginton, Donald

Shaun P. Vahey

English

Research Papers in Economics

“Keep It Real!”: A Real-time UK Macro
Data Set
Don M. Egginton
Daiwa Institute of Research Europe
Andreas Pick
University of Cambridge
Shaun P. Vahey¤
University of Cambridge
First draft: 30 June 2001
This draft: 3 September 2001
Abstract
We present a real-time macro data set for the UK. Each variable has many diﬀerent
vintages—reﬂecting the revisions and updates that occur over time. Our aim
is to provide a resource for researchers evaluating UK forecasting performance
and policy-making in real time. We illustrate the importance of these data by
analysing their impacts on UK inﬂation forecasts and monetary policy in the late
1980s. We ﬁnd that, contrary to the view of contemporary policy-makers, the
initial measurements of demand-side macro variables did not disguise inﬂationary
pressures.
Keywords: Data revisions; Real-time data; Inﬂation forecasts
JEL classiﬁcation: C8; E37; E52
¤Correspondence to: Shaun Vahey, Faculty of Economics and Politics, University of Cam-
bridge, Austin Robinson Building, Sidgwick Avenue, Cambridge, UK, CB3 9DD. E-mail:
shaun.vahey@econ.cam.ac.uk, Fax: +44 (0)1223 335475. We thank David Hendry, Simon
Price, Ken Wallis, Rod Whittaker and participants at the Warwick Macro Modelling Sem-
inar 2001 for helpful comments. We are grateful to Mark Green, Elena Loukoianova and
Patricio Feres for research assistance. The real-time macroeconomic data are available from
http:= =www.econ.cam.ac.uk/dae/keepitreal/. Partial ﬁnancial support from the ESRC (Research
Grant No. L38251021) is acknowledged gratefully.1 Introduction
Nearly all UK macro research is based on the “most recent vintage” of data. That
is, for a given variable, the researcher uses the most recently measured values.
As the oﬃcial data producing agency—the Oﬃce for National Statistics (ONS)—
revises the ﬁgures, successive researchers, each using the most recent vintage,
analyse diﬀerent data. Furthermore, the data used by researchers for forecast and
policy evaluation diﬀer from those confronting forecasters and policy-makers in
real time.
The literature examining the impact of data revisions has a long tradition
including Zellner (1958), Stekler (1967) and Harvey et al. (1983). A series of
papers by Patterson and Hervai (1991b, 1991a) and Patterson (1994, 1995) have
examined the relationship between diﬀerent vintages of UK data for a variety of
time series. Real-time data have been used by a number of researchers for policy
analysis including Orphanides and van Norden (1999) and Orphanides et al. (2000)
(output gaps), and Orphanides (2000) (Taylor rules).
The only existing source of multiple variable real-time data that we are aware
of refer to the US and were compiled by the Federal Reserve Bank of Philadelphia.
The data are available at http:= =www.phil.frb.org/econ/forecast/; data descriptions
are provided by Croushore and Stark (1999, 2000). In this paper, we present
a complementary real-time macro data set for the UK. The data can be down-
loaded from http:= =www.econ.cam.ac.uk/dae/keepitreal/, together with detailed de-
scriptions. We demonstrate the importance of using real-time data by examining
the impacts on UK inﬂation forecasts and monetary policy in the late 1980s.
2 Data details
Typically, macro data sets contain only the most recent vintage of a given time
series variable, with the data recorded as a column (or row) vector. In our real-
time data set, for each variable, the data are stored as a matrix. Each successive
column vector of the matrix represents a new vintage of data, containing the
most recent measurements available at that vintage date. The data are stored
by variable and were collected by examining various issues of Economic Trends
and Financial Statistics, both of which are published by the ONS (formally the
Central Statistical Oﬃce). The ﬁgures reported were in the public domain at the
end of the month in question. For each vintage, the observations are identical to
those in the relevant published source.1
The variables comprise: (real) GDP, (real) consumers’ expenditure, unem-
ployment, (real) industrial production, retail sales (volume), monetary aggregates
(M0, M3, M4), budget deﬁcit (public sector borrowing requirement) and average
earnings. The ﬁrst two variables are quarterly; the remainder are monthly. With
the exception of the money ﬁgures, the ﬁrst vintage is January 1980 and the last is
1Unfortunately, the window length reported by the source publications is aﬀected by page
layout considerations—it varies by variable and by vintage date. Missing data are recorded as
empty cells.
1June 1999. Reﬂecting availability in the source publications, for M0, M3 and M4
the ﬁrst vintages are June 1981, January 1980 and June 1987 and the last vintages
are June 1999, August 1989 and June 1999 respectively. All (vintage dependent)
ONS codes are available from the website.
The size and number of revisions to UK macro data have been sources of much
concern, particularly during the late 1980s. An oﬃcial scrutiny into the quality
of data was conducted in 1988. The “Pickford Review” proposed a number of
reforms designed to improve the quality of macro statistics, many of which were
adopted over the next decade (see Wroe (1993) for details). Kenny and Rizki
(1992) and Wroe (1993) document the extent of revisions to various ONS series.
A number of researchers, including Johnson (1991) and Smith (1992) have argued
that the quality of UK macro statistics deteriorated in the late 1980s, with initial
measurements of key variables subject to downward bias. Policy-makers at both
HM Treasury and the Bank of England felt that this bias—something more than
previously experienced mean zero measurement error—delayed the tightening of
monetary policy in the late 1980s, contributing to the inﬂationary boom (see, for
example, Hibberd (1990) and Leigh-Pemberton (1990)).
3 A case study: UK inﬂation forecasts in the late 1980s
In order to assess the impact of using real-time data on inﬂation forecasts, we
utilise two distinct data sets, distinguished by the vintages used but containing
common macro indicators. The ﬁrst is based on the most recent vintage available
currently (July 2001) for each variable. Henceforth, we refer to these data as
“current vintage”. The second is based on the most recent vintages available in
real time—we refer to these data as “real-time vintage”.
We restrict our consideration to the following base set of macro indicators
(where ∆ denotes the year-on-year growth rate)2: INFL (inﬂation), ∆FT (FT all-
share index), ∆EM (£-DM exchange rate), ∆ED (£-US$ exchange rate), USSP
(US yield spread), ∆TBILL (change in UK 3-month treasury bill rate), ∆HP
(house prices), CP (commodity prices), ∆PPI (producer output prices), ∆U (un-
employment), ∆IP (real industrial production), ∆M0 (money supply), ∆GDP
(real gross domestic product), and ∆C (real consumers’ expenditure). Full details
of the variables used, including the ONS mnemonics, can be obtained from the
website, together with the data themselves. All variables are available monthly
except consumers’ expenditure and GDP which are available quarterly. To obtain
monthly series for these variables we interpolate linearly (but not extrapolate) the
quarterly year-on-year growth rates using the nearest quarterly observations.
We generate out-of-sample inﬂation forecasts for the late 1980s by utilising a
recursive modelling strategy (Pesaran and Timmermann 1995). Our approach is
based on the view that inﬂation can be forecast by exploiting statistical relation-
ships with a variety of macro indicators and that these relationships may vary over
2Clearly, the set of variables that can be used to forecast inﬂation is very large. For example,
Wallis et al. (1987) describes the (quarterly) HM Treasury Model as having 700 equations and
1275 variables. For computational reasons, we use a (much) more parsimonious base set.
2the business cycle. Given the well-documented economic reforms and switches in
intermediate macro targets in the period (see, for example, Johnson (1991)), it is
very unlikely that one inﬂation forecasting model held throughout.3
We model a typical forecaster searching for a satisfactory empirical speciﬁca-
tion among the many believed to be useful for predicting inﬂation over the period
from April 1982 to October 1990. We use observations from April 1982 to De-
cember 1986 as a “training period”; and make 12-month ahead forecasts for the
period January 1988 to October 1990. The start of the sample was chosen to
exclude the early 1980s recession; the end reﬂects the resignation of Nigel Lawson
as Chancellor and an associated change in monetary policy in October 1989.
Using the real-time vintage data, in every period, denoted ¿, from January
1987 to October 1989, we estimate the following linear models by OLS:
¼t = ®i + ¯0
ixi;t¡12 + "i;t; i = 1;:::;2k; t = 1;:::;¿¡1;
where ¼t is the 12-month growth rate of RPIX from t¡12 to t.4 The subscript
i refers to the 16384 diﬀerent models estimated in each period ¿—one for each
of 2k combinations of the k = 14 macro indicators in the base set. Each model
is identiﬁed by a unique combination of macro indicators included in xi;t¡12. All
macro variables are contained within the information set at t¡12, i.e. each variable
is dated such that the most recent publicly available observation at t ¡ 12 is
included. In every period, ¿, we use the Akaike Information Criterion (AIC) to
select a preferred model from the many models estimated.5 The resulting optimal
models, one for each period from January 1987 to October 1989, are used to
construct our forecasts for January 1988 to October 1990 (¼¿+12).
For comparison, we repeat this recursive model selection and forecast pro-
cedure using current (rather than real-time) vintage data. The resulting two 12-
month ahead forecast series, one for each data set, are shown in Figure 1. For most
of the forecast period, the real-time forecasts exceed those based on the current
vintage. That is, a forecaster using real-time data would have predicted stronger
inﬂationary pressures than a researcher looking back at the period using the cur-
rent vintage. At ﬁrst pass this ﬁnding seems surprising. Kenny and Rizki (1992)
and Wroe (1993) show that the initial measurements of a number of demand-side
macro variables were biased downwards. Assuming that the estimated model pa-
rameters were the same for both data types, real-time vintage data would result
in weaker evidence of inﬂationary pressure. In fact, the estimated parameters
(and models) using the real-time vintage are very diﬀerent from those using the
current vintage. Notice also that by visual inspection, the real-time forecasts ex-
3A single more structural model, such as that in Hendry (2001), may produce superior fore-
casts; but, given that our focus is out-of-sample performance in the presence of structual change,
it may not.
4The growth in RPIX is currently the Bank of England’s preferred measure of underlying
inﬂation. It excludes the component of the RPI involving mortgage interest payments. The
impacts of revisions on RPI rather than RPIX inﬂation forecasts are similar. Details can be
obtained from the authors on request.
5Results using other information criteria are similar and are available from the authors on
request.
3hibit greater volatility than the current vintage forecasts, reﬂecting the volatility
in both the data and the estimated coeﬃcients.
It is clear from Figure 1 that UK inﬂation was diﬃcult to forecast out of sample
in the late 1980s. Both forecasts series suggest (varying degrees of) forecast failure.
It is interesting to note that a variety of independent forecasts and the public HM
Treasury forecasts reported in Treasury Select Committee (1991) were similarly
aﬄicted.6
Undoubtedly, inﬂation forecast failure contributed to the well-documented fail-
ure of monetary control in the late 1980s. Nigel Lawson, Chancellor in our forecast
period, famously suggested in his 1985 Mansion House speech that “(t)he acid test
of monetary policy is its record in reducing inﬂation ::: The inﬂation rate is judge
and jury” (Lawson 1992, p.481). Yet RPIX inﬂation—Lawson’s preferred measure
of underlying inﬂation (Lawson 1992, p.480)—increased steadily from July 1986
until Lawson’s resignation in October 1989. Figure 1 suggests that contrary to
the contention of Hibberd (1990) and Leigh-Pemberton (1990), the downward bias
in the initial measurements of demand-side variables did not disguise inﬂationary
pressures in the late 1980s. Quite the reverse; using real-time data, for most of
the period under consideration, the evidence of lack of monetary discipline was
somewhat stronger.
This episode in UK monetary policy can be used to illustrate the importance
of using real-time data for policy evaluation. Consider a researcher assuming that
Lawson followed an RPIX inﬂation forecast target of 4.5 percent or less (the rate
prevailing when he started as Chancellor in July 1983). If our researcher believed
that Lawson could reasonably have made the forecasts shown in Figure 1, then
she would conclude that policy errors were made whenever the 12-month ahead
forecasts exceeded the target. Using the current vintage forecasts, this occurred
twice in our forecast period: between May 1987 and September 1987 (12-month
ahead forecasts reported dated May 1988 and September 1988); and again from
February 1989 to the end of the sample. Using the real-time vintage forecasts, the
policy errors occurred later in the ﬁrst case, July 1987 to October 1987 (arguably,
Febuary 1988), and earlier in the second case, October 1988 to the end of the
sample.7
Of course, in reality, non-inﬂation related objectives (at times) played a part
in Lawson’s setting of monetary policy. The candidates include growth (in par-
ticular, avoiding a recession following the 1987 stock market crash), tax reforms
and exchange rates targets. Since our aim is to demonstrate that real-time data
matter for forecast and policy evaluations, we leave these issues to be explored in
a more complete real-time study of UK monetary policy in the late 1980s.
6The forecast failure of our models is driven partly by the assumption that inﬂation is sta-
tionary in the (short) period under consideration. Ex post, it is clear that modelling inﬂation as
non-stationary improves forecasting performance but, arguably, such an assumption is inconsis-
tent with the notion of real-time monetary control.
7Actual base rates were raised repeatedly in the second half of 1988 from 8.9 percent to 12.9
percent. This continued though 1989 to a peak of 14.9 percent. Apparently this was insuﬃcient
to oﬀset inﬂationary pressures.
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Keep It Real!: A Real-time UK Macro Data Set

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