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FRBSF ECONOMIC LETTER
2016-03

February 8, 2016

Will the Economic Recovery Die of Old Age?
BY

GLENN D. RUDEBUSCH

Is the current recovery more likely to end because it’s lasted so long? Have various imbalances
and rigidities accumulated to make the economy frailer and more susceptible to a recessionary
shock? Recent history suggests the answer is no. Instead, a long recovery appears no more
likely to end than a short one. Like Peter Pan, recoveries appear to never grow old.

Recent economic indicators show that U.S. economic growth has slowed considerably. After adjusting for
inflation, aggregate output increased little during the final three months of 2015. Is this the start of a
serious stumble by an aging economy with creaky knees? Are we due for a recession? Or is the slowdown
just part of the normal ups and downs of a healthy, dynamic economy?
Recessions are notoriously difficult to forecast. However, much conventional wisdom views an aging
expansion as increasingly fragile and more likely to end in recession. The associated predictions of
recession—proclaiming that “it’s about time” for a downturn—have become more prominent lately because
the current recovery, which started six and a half years ago, is relatively long already. For example,
Rebecca Jarvis from ABC News asked Federal Reserve Chair Janet Yellen about this issue at the most
recent Federal Open Market Committee press conference (Board of Governors 2015):
REBECCA JARVIS: Historically, most economic expansions fade after this long. How confident are
you that our economy won’t slip back into recession in the near term?
CHAIR YELLEN: …I think it’s a myth that expansions die of old age. I do not think that they die of
old age. So the fact that this has been quite a long expansion doesn’t lead me to believe
that…its days are numbered.
The notion that business expansions are more likely to end as they grow older was especially common
before World War II. Gottfried Haberler’s (1937) classic synthesis of prewar business cycle theories
devotes an entire section to the topic: “Why the Economic System Becomes Less and Less Capable of
Withstanding Deflationary Shocks After an Expansion Has Progressed Beyond a Certain Point.”
Nowadays, the underlying rationale for this view follows an analogy to human mortality: As the expansion
ages, assorted imbalances and rigidities accumulate that hobble the economy and make it more fragile.
Thus, the recovery could be jeopardized by ever smaller shocks, and it becomes more likely over time that
the economy will fall into recession.
However, the historical record since World War II does not support the view that the probability of
recession increases with the length of the recovery. The earliest statistical investigation of the issue by
Diebold and Rudebusch (1990) found that postwar expansions were not more likely to end as they
endured. This Economic Letter updates that analysis. The results concur with Yellen’s view that, all else
equal, longer expansions are no more likely to end than shorter ones.

FRBSF Economic Letter 2016-03

February 8, 2016

Calculating the probability of dying of old age
Survival analysis—also known as duration or reliability analysis—is a branch of statistics that examines the
probabilities of events, such as the death of a biological organism, the failure of a machine, or the
acquisition of a job. The analysis focuses on how such probabilities change over time. For example,
survival analysis implicitly plays an important role in the used car market. All else equal, as a car ages, the
probability that it will suffer a mechanical breakdown increases. Thus, older cars are considered less
reliable and generally command a lower price in the marketplace. Understanding the relationship between
the age of a vehicle and the likelihood of its breakdown is a simple application of survival analysis.
Survival analysis is also widely applied to human mortality rates in life insurance calculations. A key
insight from this type of analysis is that the probability of death at any point in time can be inferred from
the distribution of the actual lifetimes recorded for a population. Therefore, a demographer can calculate
mortality rates at various ages by examining the age distribution of those who died.
Like other pension administrators, the Social Security Administration uses these statistical methods. Their
estimates of mortality rates for U.S. males are shown in Figure 1. These rates give the probability that a
man of a certain age will die during the
Figure 1
subsequent year. For example, a 50Probability of a person dying within a year
year-old man has a ½% chance of dying
Males, based on 2011 actuarial tables
during the next year, while a 90-yearPercent
100
old has a 17% chance. Put another way,
90
a 50-year-old man has a 99.5% chance
80
of surviving another year, while a 9070
year-old has only an 83% chance.
60
50
How mortality rates vary with age is of
40
particular interest. From childhood to
30
around age 65, there is only a very
20
modest increase in mortality rates. Over
10
that range, the likelihood of dying is
0
little affected by age, so the probability
0
10 20 30 40 50 60 70 80 90 100 110 120
of death effectively exhibits no age or
Age in years
duration dependence. However, after
age 65, the likelihood of dying rises markedly with age. That is, above the age of 65, the probability of
death shows increasing age dependence, also known as positive duration dependence. Indeed, after age
107, death in the following year becomes more likely than survival. Of course, as in other contexts, these
mortality rate curves are not set in stone. Advances in medicine and public health have allowed people to
live longer and caused the curve in Figure 1 to steadily shift to the right for more than a century.

Do economic recoveries die of old age?
The techniques of survival analysis are well-suited to investigating the probability that a business
expansion will end, as described by Diebold and Rudebusch (1990) and Sichel (1991). In this application,
the event being predicted is a business cycle peak, which marks the end of a recovery and the start of the
subsequent recession. In particular, it will be possible to calculate whether this probability increases with
the age of the expansion.

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FRBSF Economic Letter 2016-03

February 8, 2016

The raw data for this calculation are the lengths of past business expansions—similar to the human
lifetimes used earlier. The durations of expansions in the United States since World War II are shown in
Figure 2. They are determined by the National Bureau of Economic Research (NBER), which dates the
beginning and end of each expansion. According to the NBER, the last recession in the United States—the
Great Recession—ended in June 2009. Since then, the recovery has lasted six and a half years, which is
substantially longer than most previous business expansions. This ongoing recovery is shown in red, and
its end date is noted as a question mark. Other postwar expansions range from 12 months for the 1980–81
recovery to 10 years for the long boom of the 1990s. Very short expansions—say, only eight months long—
are never observed because the NBER requires an upturn in business activity to surpass a minimum
duration of almost a year before it can be formally designated as an expansion.
As in the human mortality study, the
statistical techniques of survival analysis
can be used to translate these durations
into expansion mortality rates, that is,
conditional probabilities that an
expansion will end in the subsequent
month given that it has lasted so long
already. The dark blue line in Figure 3
shows the estimated mortality rates for
postwar expansions, calculated
assuming the widely used Weibull
probability distribution. For example,
Figure 3 shows that a 50-month-old
expansion has a 2% chance of ending in
the next month or, if this probability is
cumulated over the next 12 months, the
expansion has about a 23% chance of
ending during the next year. These
calculations take into account the fact
that very short expansions are truncated
in the data and that the current recovery
is ongoing.

Figure 2
Durations of postwar expansions
Date
1980-1981
1958-1960
1970-1973
1945-1948
1954-1957
1949-1953
1975-1980
2001-2007
20092009-??
1982-1990
1961-1969
1991-2001
0

20

40
60
Age in months

80

100

120

Figure 2
Probability of a recovery ending within a month
Percent
25
20

Prewar
expansions

15

It is notable that the line for postwar
10
expansions in Figure 3 is nearly flat—
like the early human mortality rates in
Postwar
5
Figure 1. This means that the mortality
expansions
rates for postwar expansions don’t really
depend on the length of the expansion.
0
0
10 20 30 40 50 60 70 80 90 100 110 120
Indeed, a statistical test cannot reject
Age in months
the hypothesis that the dark line really is
flat and that the probability of a recession in any month is independent of the age of the recovery.
Accordingly, based only on age, an 80-month-old expansion has effectively the same chance of ending as a
40-month-old expansion. Therefore, the current recovery is no more likely to end simply because it’s
approaching its seventh birthday.

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FRBSF Economic Letter 2016-03

February 8, 2016

In contrast, the same statistical technique yields very different results when applied to prewar expansions
from 1854 to 1938. As shown by the red line in Figure 3, mortality rates for expansions before World War
II increased with the length of the expansion. This positive duration dependence means that prewar
expansions were more likely to end as they grew older. The evidence that duration dependence
disappeared from the prewar to postwar periods has been supported by further work in Diebold and
Rudebusch (1999) and the more recent studies listed in Castro (2013).
Several postwar changes in the economy contributed to more robust and longer-lived expansions. One
such change is the increased share of services instead of tangible goods in the economy’s output; this
would tend to diminish the importance of inventory fluctuations and moderate the business cycle. Even
more importantly, the postwar shift to less fragile recoveries reflects the new influence of a large federal
government actively focused on stabilizing the economy. For example, a new postwar full-employment
mandate, the Employment Act of 1946, applied broadly to the federal government, including to the Federal
Reserve and in the conduct of monetary policy (Judd and Rudebusch 1999). The postwar change in
macroeconomic management away from a laissez-faire hands-off attitude toward a forceful countercyclical
policy helped prolong business expansions and alter the pattern of business cycle age dependence.
Furthermore, the federal commitment to macroeconomic stabilization also included attempts to curtail
recessions. This is consistent with additional evidence in Diebold and Rudebusch (1990) that postwar
economic recessions show more duration dependence than prewar ones. In other words, as postwar
recessions age, they become more likely to end as policymakers take action to revive growth.
Conclusion
Empirical evidence indicates that expansions during the past 70 years do not become progressively more
fragile with age. This evidence supports the view of Fed Chair Yellen that the current recovery is not living
on borrowed time. Expansions, like Peter Pan, endure but never seem to grow old.
Glenn D. Rudebusch is director of research and executive vice president in the Economic Research
Department of the Federal Reserve Bank of San Francisco.
References
Board of Governors of the Federal Reserve System. 2015. “Transcript of Chair Yellen’s Press Conference, December
16, 2015.” Washington, DC. http://www.federalreserve.gov/mediacenter/files/fomcpresconf20151216.pdf
Castro, Vitor. 2013. “The Duration of Business Cycle Expansions and Contractions: Are There Change-Points in
Duration Dependence?” Journal of Empirical Economics 44, pp. 511–544.
Diebold, Francis X., and Glenn D. Rudebusch. 1990. “A Nonparametric Investigation of Duration Dependence in the
American Business Cycle.” Journal of Political Economy 98 (June), pp. 596–616.
Diebold, Francis X., and Glenn D. Rudebusch. 1999. Business Cycles: Durations, Dynamics, and Forecasting.
Princeton: Princeton University Press.
Haberler, Gottfried. 1937. Prosperity and Depression: A Theoretical Analysis of Cyclical Movements. Geneva: League
of Nations.
Judd, John, and Glenn D. Rudebusch. 1999. “The Goals of U.S. Monetary Policy.” FRBSF Economic Letter 1999-04
(January 29). http://www.frbsf.org/economic-research/publications/economic-letter/1999/january/the-goalsof-us-monetary-policy/
Sichel, Daniel. 1991. “Business Cycle Duration Dependence: A Parametric Approach.” The Review of Economics and
Statistics 73(2), pp. 254–260.

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FRBSF Economic Letter 2016-03

February 8, 2016

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