I heard Dr. Robert Barro spech on this subject.. It is about phase delay and the imput of huge cash has taken about 6.5 years to clear the banks bad debts in the past... As stated in the Introduction we see a "Fat Tail of risk" vs Bayesian curve... Sorry but I disagree with Dr. Barro on this part of the subject...Bruce VR it is also about efficiency and the USA is the world leader .. The not world class will be the not in business , real soon. UAW is looking at this as Alabama is starting to overtake the USA auto production in America of none American firms.
We estimate an empirical model of consumption disasters using a new panel data set on
consumption for 24 countries and more than 100 years. The model allows for permanent and
transitory effects of disasters that unfold over multiple years. It also allows the timing of disasters
to be correlated across countries. We estimate the model using Bayesian methods. Our estimates
imply that the probability of entering a disaster is 1.7% per year and that disasters last on
average for 6.5 years. In the average disaster episode identified by our model, consumption falls
by 30% in the short run. In the long run, roughly half of this fall in consumption is reversed.
Disasters also greatly increase uncertainty about consumption growth. Our estimates imply a
standard deviation of consumption growth during disasters of 12%. We investigate the asset
pricing implications of these rare disasters. In a model with power utility and standard values
for risk aversion, stocks surge at the onset of a disaster due to agents’ strong desire to save. This
counterfactual prediction causes a low equity premium, especially in normal times. In contrast,
a model with Epstein-Zin-Weil preferences and an intertemporal elasticity of substitution equal
to 2 yields a sizeable equity premium in normal times for modest values of risk aversion.
Keywords: Rare disasters, Equity premium puzzle, Bayesian estimation.
JEL Classification: E21, G12
∗
We would like to thank Timothy Cogley, Xavier Gabaix, Martin Lettau, Frank Schorfheide, Alwyn Young, Tau
Zha and seminar participants at various institutions for helpful comments and conversations. Barro would like to
thank the National Science Foundation for financial support.
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Introduction
The average return on stocks is roughly 7% higher per year than the average return on bills across
a large cross-section of countries in the twentieth century (Barro and Ursua, 2008). Mehra and
Prescott (1985) argue that this large equity premium is difficult to explain in simple consumption-
based asset-pricing models. A large subsequent literature in finance and macroeconomics has sought
to explain this “equity-premium puzzle”. One strand of this literature has investigated whether the( Barro states 7% vs 4.5% used in my model from NUY and MMXI)
MOST HERE KNOW I AM RISK ADVERSE.. MOST ARE NOT AND USE THE 7%..correct ROVO)
equity premium may be compensation for the risk of rare but disastrous events. This hypothesis
was first put forward by Rietz (1988).1 A drawback of Rietz’s paper is that it does not provide
empirical evidence regarding the plausibility of the parameter values needed to generate a large
equity premium based on rare disasters.
Barro (2006) uses data on GDP for 35 countries over the 20th century from Maddison (2003)
to evaluate Rietz’s hypothesis empirically. His main conclusion is that a simple model calibrated
to the empirical frequency and size distribution of large economic contractions in the Maddison
data can match the observed equity premium. In subsequent work, Barro and Ursua (2008) have
gathered a long-term data set for personal consumer expenditure in over 20 countries and shown
that the same conclusions hold using these data. Barro (2006) and Barro and Ursua (2008) analyze
the effects of rare disasters on asset prices in a model in which consumption follows a random
walk, disasters are modeled as instantaneous, permanent drops in consumption, and the timing of
disasters is uncorrelated across countries. They show that it is straightforward to calculate asset
prices in this case.
The tractability of the models used in Barro (2006) and Barro and Ursua (2008) comes at the
cost of empirical realism in certain respects. First, their model does not allow for recoveries after
disasters. Gourio (2008) argues that disasters are often followed by periods of rapid growth. A
world in which all disasters are permanent is far riskier than one in which recoveries often follow
disasters. Assuming that all disasters are permanent therefore potentially overstates the asset-
pricing implications of disasters. Second, their model assumes that the entire drop in consumption
due to the disaster occurs over a single time period, as opposed to unfolding over several years as in
the data.2 Third, their model assumes that output and consumption follow a random walk in normal
1
Other prominent explanations for the equity premium include models with habits (Campbell and Cochrane,
1999), heterogeneous agents (Constantinides and Duffie, 1996) and long run risk (Bansal and Yaron, 2004).
2
This assumption is criticized in Constantinides (2008).
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times as well as times of disaster. A large literature in macroeconomics has debat
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