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THE OPENNESS-INFLATION PUZZLE REVISITED

William C. Gruben
Darryl McLeod

Center for Latin American Economics
Working Paper 0203
Center for Latin American Economics
Working Paper 0201
March 2003

FEDERAL RESERVE BANK OF DALLAS

The Openness-Inflation Puzzle Revisited

William C.Gruben+ and Darryl McLeod*

+

Center for Latin American Economics, Federal Reserve Bank of Dallas,
P.O. Box 655906, 2200 North Pearl Street, Dallas, TX 75201-2272, USA

*

Department of Economics, Fordham University, 441 East Fordham Road, NY 10458-5158, USA

E-Mail: william.c.gruben@dal.frb.org; mcleod@fordham.edu

Dynamic panel estimates show the negative relation between trade openness and inflation found by
Romer (1993) but questioned by Terra (1998) became more robust in the 1990s, both among high
income OECD and developing countries. Also during the 1990s, openness was associated with less
variable inflation and had a stronger disinflation effect in economies with floating exchange rates.

*Corresponding author:

Darryl McLeod
Economics Department
441 East Fordham Road
NY, NY 10458 USA
718 817-4063
mcleod@fordham.edu

The Openness-Inflation Puzzle Revisited
Romer (1993) finds closed economies tend to have higher inflation. Central banks in
economies more open to trade, Romer argues, find currency fluctuations caused by money surprises
more painful and therefore exercise more restraint than their closed economy counterparts. While
some question Romer’s dynamic inconsistency story,1 the openness-inflation correlation itself has
generated considerable interest. Temple (2002) calls it one of the modern “puzzles” of international
macroeconomics. But Terra (1998) challenges Romer’s empirical findings, arguing that the
openness inflation correlation is confined to severely indebted countries and, even then, is only
evident during the 1980’s debt crisis period. Romer (1993) himself finds no significant inflationopenness relationship among OECD economies.2
This note revisits Romer and Terra’s findings in a more general dynamic panel setting using
data from the 1990s. Our results suggest the negative openness-inflation correlation strengthened in
the 1990s across all country groups. And contrary to Terra’s (1998) hypothesis, except during
1980s, the inflation-openness relationship is more significant among less indebted countries. More
open economies also tend to have less variable inflation, albeit only in the 1990s. Arellano-Bover
GMM panel system estimates using five-year averages suggest causality runs from openness to
lower inflation, as Romer (1993) argued. The disinflation effect of openness appears to be stronger
in countries with floating exchange rates. These results support the view that trade openness
reduces inflation generally, and that it did, in particular, during the worldwide disinflation of the
1990s.
Among the skeptics is David Romer himself, see his Advanced Macroeconomics 2nd edition, page 492.
Lane (1997), however, finds that after controlling for country size, inflation is negatively correlated with
openness among OECD countries. Similar results are reported in Table 3 below.
1
2

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Our panel consists of five-year averages for inflation and import shares over the period
1971-2000, effectively encompassing Romer and Terra’s 1973-89 cross-country averages.
Following Terra (1998) we focus mainly on bivariate inflation and openness relationship, albeit in a
more general dynamic panel framework.3 Table 1 addresses Terra’s hypothesis regarding the role
of external debt by separating our panel into severely and less indebted countries and reporting
results for the 1980s debt crisis period separately.4 The four upper right entries in Table 1 tell the
story. Consistent with Terra (1997), there is a strong inflation-openness correlation among severely
indebted countries in the 1980s. But outside the debt crisis period, the pattern reverses. Excluding
the 1980s, the coefficient for the severely indebted countries is larger: -.30 compared to -.10 for less
indebted countries, but is no longer statistically significant even at the 10% level. The not-severelyindebted countries coefficient for the same period is, on the other hand, highly significant.
Table 2 tests the robustness of the inflation-trade openness relationship. Changes in fiveyear average inflation rates and import shares are regressed on lagged values of the same variables,
plus some time period dummies using Arellano and Bover’s (1995) GMM dynamic panel system
estimator. Note that lagged changes in trade shares predict inflation, but the reverse is not true.
When import shares increase, inflation tends to fall in the next period. Equation 2.6 tests for
spurious correlations caused by inflation induced real exchange rate changes. The openness
measure in Equation 2.6 is the “open” variable from the Penn World Tables Version 6.1: total
imports plus exports over GDP.5 The PWT trade shares are measured in constant international
3

These results are robust to the addition of structural variables such as per capita income, latitude, total PPP
GDP (size) and regional dummies see Gruben and McLeod (2002) and Lane (1997). However, many of the
variables used in these cross-country regressions are not available in time series or for the 1990s (Central
Bank independence measures for example).

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prices, and therefore are less influenced by short-term real exchange rate fluctuations. Evidently,
the negative inflation-openness correlation holds for this broader openness measure as well.6
Following Romer (1993), a number of models explaining the openness-inflation correlation
have been proposed. Lane (1997) and Guender and McCaw (2000) stress nominal rigidities or
market imperfections that cause nominal exchange rate movements to have real effects. Similarly,
Temple (2001) and Bowdler (2003) focus on exchange rate movements that worsen the tradeoff
between money surprises and unemployment. Equation 2.4 splits the import trade share among
three classifications of exchange rate flexibility. The magnitude of the inflation-openness
coefficient increases with the degree of exchange rate flexibility. The difference between the pure
floaters and the fixed exchange rate regime coefficient is significant at the 5.1% confidence level.
Terra (1997) argues that highly indebted countries use seigniorage to pay off debt, a strategy
that is less inflationary in more open economies. To test this proposition, Equation 2.3 splits the
import share variable into three country groups defined by levels of external indebtedness. The
coefficient for severely indebted countries is higher than that for the less indebted countries, but
differences among the coefficients are significant at the 10% confidence level.
The inflation-openness correlation appears to strengthen in the 1990s. The time-varying
coefficients reported in Table 3 suggest that countries most open to trade saw the greatest reduction
in their inflation rates during the 1990s.7 Additional evidence for the 1990s is provided by Equation
6

Using the World Bank WDI 2002 imports of goods and services over its PPP GDP estimates yields similar
results, but the World Bank WDI only includes PPP GDP estimates from 1975 on, so using the PWT 6.1
openness measures provides a larger data set.
7

/ Between the late 1980s and the late 1990s, the weighted average import share for the 118 countries in our
sample rose from 19% to 24% of GDP while the weighted average inflation rate fell from 70% to 5%.

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2.5 where the dependent variable is now the coefficient of variation8 for inflation. After 1985,
economies more open to trade also had less variable inflation.
To summarize, the inflation-trade openness correlation appears to have strengthened during
the 1990s and is more robust than earlier research suggested—extending even to OECD countries.
Yet why we observe this relationship remains something of puzzle. David Romer (2000, p. 492)
seems less convinced this correlation emanates from the “inconsistency of optimal [central bank]
plans.” Other explanations are being explored. Bowdler (2003) finds openness makes the shortterm Phillips curve steeper in OECD countries. Temple (2002) argues that it generally does not.
Gruben and McLeod (2001) argue openness raises the interest rate elasticity of money demand,
reducing the optimal inflation tax. Another possible explanation is disinflation contagion: with U.S.
and OECD inflation falling during the 1990s, the disciplining effect of import competition may
have enabled more open economies to lower inflation faster. Whatever its cause, that greater
openness to trade is associated with lower inflation should provide some comfort to those who fear
globalization and flexible exchange rates increase macroeconomic instability.
8

/ The coefficient of variation is the standard deviation of the log of one plus the inflation rate divided by
mean inflation for 1986-90, 1991-95 and 1996-2000.

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REFERENCES
Arellano, M. and Bover, O. (1995) Another look at instrumental variables estimation of Error
Component Models, Journal of Econometrics 68 , 29-51.
Bowdler, C. (2003) Openness and the output-inflation Tradeoff, Nuffield College, Oxford
University, Mimeo.
Gruben, W., and McLeod, D. (2001) Capital account liberalization and 1990s disinflation , Center
for Latin American Economics Working Paper 0101, Federal Reserve Bank of Dallas.
Guender, A., and McCaw, S. (2000) The inflationary bias in a model of the open economy,
Economics Letters 68, 173-78.
Lane, P. (1997) Inflation in open economies, Journal of International Economics 42, 327-347.
Romer, D. (1993) Openness and inflation: Theory and evidence, Quarterly Journal of Economics
CVIII, 869-903.
Romer, D. (1998) A new assessment of openness and inflation: Reply, Quarterly Journal of
Economics CXIII, 649-652.
Romer, D. (2000) Advanced Macroeconomics, Second edition, (New York, McGraw Hill)
Temple, J. (2002) Openness, inflation, and the Phillips curve: A puzzle, Journal of Money, Credit,
and Banking 34, 450-68.
Terra, C. (1998) Openness and inflation: A new assessment,” Quarterly Journal of Economics
CXIII, 641-648.

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Table 1
Inflation and Openness to Trade: 1971-2000 5-year Averages
Pooled OLS:
Period:
Country Group
1.1 Not Severely Indebted Countries
Number of observations

1.2 Severely Indebted Countries
Number of observations
1.3 All Countries
Number of observations

1971-2000 2/
All Years

1981-1990
Debt Crisis

71-80 & 91-00
Non-Debt Crisis

-0.09

-0.064

-0.10

(.022)**

(.033)*

(.028)**

472

165

307

-0.61

-1.14

-0.30

(0.23)**

(0.47)**

(0.23)

193

70

123

-0.23

-0.35

-0.17

(0.05)**

(0.11)**

(0.058)**

665

235

430

1/ Standard errors in parentheses. **Significant at the 5% or *10% level. Openness is imports of goods and
services as a percent of GDP converted to dollars using market exchange rates as reported in the World
Bank’s WDI 2002 CD-Rom. The sample of countries is Romer’s (1993) 114 countries plus Hungary,
Grenada, The Solomon Islands and Cape Verde – as added by Terra (1998). The five-year averages include
1971-75,76-80,…96-00. Missing WDI deflators and import shares were supplemented with IMF’s
International Financial Statistics November 2002 CD-Rom data for Bahrain, Cape Verde, Democratic
Republic of the Congo, Cyprus, Ethiopia, Grenada, Guyana, Jordan, Kuwait, Iran, Liberia, Oman, Panama,
Solomon Islands, Somalia, Sudan, Yemen, and Zimbabwe. Taiwan data is from Council for Economic
Planning and Development, Taiwan Statistical Data Book 2001. The complete data set is available at
www.fordham.edu/economics/mcleod.
2/ Similar results are obtained for fixed and random effects panel estimates. Bivariate pooled OLS are
reported here to be as consistent as possible with the methods of Romer (1993) and Terra (1998).

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Table 2:
Panel Regressions: Five-year Averages 1971-2000
2.1

2.2

2.3
1/

2.4
1/

Log
Import share

Inflation
log(1+π)

Inflation
log(1+π)

Estimation Method

GMM-SYS5/

GMM-SYS5/

OLS

Trade Openness

0.41 1/

Dependent Variable:

Lagged: previous 5 yr period

Lagged Inflation
(previous 5 year period)

2.6

Inflation
Coefficient Inflation 1/
log(1+π) of Variation6/ log(1+π)
SUR

OLS

-0.17

-5.0

-0.12 7/

(0.20)

(.05)

(1.23)

(0.03)

-0.04

0.45

-0.21

(.05)

(.14)

(0.65)

Import Share—LICs 2/

OLS

-0.21
(.046)

(less indebted countries & OECD)

Import Share- SICs

-0.25
(.063)

(Severely Indebted Ctys)

Openness: fixed Rate Regimes3/

-0.21

(import share for fixed regimes)

(0.05)

Openness: Floating fx Regimes 3/

-0.3

(import share for flex rate regimes)

(.07)

Constant

2.5
1/

1.84

0.67

0.25

0.27

5.85

0.25

(.68)

(.19)

(0.03)

(.04)

(1.91)

(.03)

Number of Observations
Sargan Test (P-value)

657
0.08

659
0.34

660

535

328

616

1st Order Serial-Correlation (p-value)

0.09

0.06
0.04
(0.05)

0.09
(.048)

Coefficient Difference 4/ (Wald test)

1/ To cope with deflation episodes, inflation is measured as the natural log of one plus the average annual change in the GDP deflator.
2/ Classification of less, severely and moderately indebted countries follows Terra (1998). Equation 2.3 includes a moderately indebted
group coefficient of -.20 (.07) but the difference is less significant statistically than that between less and severely indebted countries
3/ Classification of countries into fixed, floating and semi-fixed regimes uses LaFluer’s (2002) 8-level classification to classify countries
into three groups: fixed, flexible and semi-fixed. For equation 2.4 the openness coefficient for the semi-fixed group was -.28 (.08).
As La Fluer’s regime index is only available 1975-2000, our sample is reduced to five 5-year intervals.
4/ The Wald test null hypothesis is equal coefficients for the two import share variables reported above. The difference and standard
error are reported here. The significance levels for the equation 2.3 and 2.4 tests are 36% and 5.1% respectively
5/ This Arrellano and Bover (1995) system-GMM estimator regresses levels and changes in inflation/import shares on lags of the same
variables, using lagged levels as instruments for changes and vice versa. The Sargan tests validates this instrument set, but this was
not the case before we took the log of the import share and added time period dummies. The 71-75 and 96-00 time dummies were
significant with coefficients of -.037 (.017) and -.05 (.02) respectively.
6/ The coefficient of variation is standard deviation over the mean inflation for each five-year interval. The sample period for this
equation 1986-2000 – prior to 1986 this relationship disappears, due in large part to the extreme variations Latin American inflation.
7/ The openness variable in this equation is the Penn World Tables v. 6.1 “openness” variable: imports plus exports over $PPP GDP.

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Table 3
Inflation-Openness Over Time
Openness-Inflation Coefficient by Period 1/
76-80 81-85 86-90

91-95

96-00

Dependent Variable: log (1+π )

Constant

(3.1) No Severely Indebted Countries

0.17

-0.09

-0.07

-0.14

-0.14

-0.19

(0.16)

(0.65)

(0.05)

(0.052)

(0.051)

(0.051)

0.26

-0.28

-0.22

-0.19

-0.17

-0.32

(.025)

(0.11)

(.084)

(.084)

(0.083)

(0.084)

(497 observations)

(3.2) All countries
(665 observations)

(3.3) Severely Indebted Countries

0.5

-1.03

-0.8

-0.3

-0.16

-0.74

(178 observations)

(0.09)

(0.45)

(0.35)

(0.35)

(0.31)

(0.31)

(3.4) 27 OECD Countries
(160 observations)

0.13

-0.05

-0.07

-0.13

-0.18

-0.21

(0.16)

(0.07)

(0.61)

(0.06)

(0.065)

(0.066)

1/ Standard errors are in parentheses. These are OLS estimates for six 5-year intervals, 1971-2000.

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