Precautionary Saving and Consumption Smoothing across Time and Possibilities

This paper examines how aversion to risk and aversion to intertemporal substitution determine the strength of the precautionary saving motive in a two-period model with Selden/Kreps–Porteus preferences. For small risks, we derive a measure of the strength of the precautionary saving motive that generalizes the concept of "prudence" introduced by Kimball (1990b) . For large risks, we show that decreasing absolute risk aversion guarantees that the precautionary saving motive is stronger than risk aversion, regardless of the elasticity of intertemporal substitution. Holding risk preferences fixed, the extent to which the precautionary saving motive is stronger than risk aversion increases with the elasticity of intertemporal substitution. We derive sufficient conditions for a change in risk preferences alone to increase the strength of the precautionary saving motive and for the strength of the precautionary saving motive to decline with wealth. Within the class of constant elasticity of intertemporal substitution, constant-relative risk aversion utility functions, these conditions are also necessary.     

Precautionary Saving of Chinese and U.S. Households

We employ a model of precautionary saving to study why household saving rates are high in China and low in the United States. The use of recursive preferences gives a convenient decomposition of saving into precautionary and nonprecautionary components. Over 80% of China's saving rate and nearly all U.S. saving arises from the precautionary motive. The difference between U.S. and Chinese household income growth rates is vastly more important than income risk for explaining the saving rates. The key mechanism is that precautionary savers have target wealth‐to‐income ratios, and rapid income growth necessitates high saving rates to maintain the ratio.     

Precautionary saving and partially observed income

I propose an intertemporal precautionary saving model in which the agent's labor income is subject to (possibly correlated) shocks with different degrees of persistence and volatility. However, he only observes his total income, not individual components. I show that partial observability of individual components of income gives rise to additional precautionary saving due to estimation risk, the error associated with estimating individual components of income. This additional precautionary saving is higher, when estimation risk is greater. Compared with a precautionary agent who is otherwise identical, but ignores estimation risk, the rational agent consumes less at the beginning of his life, but consumes more later, because of larger wealth accumulated from savings for estimation risk. The utility cost of ignoring estimation risk is also quantified in closed form.     

Precautionary Saving and Endogenous Labor Supply with and without Intertemporal Expected Utility

We analyze precautionary saving behavior in a framework with labor and nonlabor income risks, an endogenous supply of labor, and a representation of preferences that disentangles attitudes toward risk, attitudes toward intertemporal substitution, and ordinal preferences for consumption and leisure. This preference structure allows us to disentangle and to describe in an intuitive way the different forces that determine precautionary saving “in the small” and “in the large.”     

Saving under uncertainty: A bivariate non-expected utility approach

We adopt the multivariate non-expected utility approach proposed by Yaari [1986] to provide a characterization of the comparative statics effects of greater risk aversion and of mean-preserving increases in risk on saving and borrowing in the presence of income and interest rate risk.We show that in Yaari's model, it is possible to extend the applicability of the Diamond and Stiglitz [1974] and Kihlstrom and Mirman [1974] (DSKM) single-crossing property to establish a relationship between greater risk aversion and saving (or borrowing) on the basis of the individual's ordinal preferences as long as the two risks are independent. We also demonstrate that the comparative statics effects of a joint mean-preserving increase in random income and interest rate on saving and borrowing can be determined by an extension of the DSKM single-crossing property.     

城镇居民预防性储蓄动机强度的再认识

国内需求的萎靡不振已成当前经济学界的一个热点问题,而城镇居民储蓄的高速增长与此紧密相连,预防性储蓄强度在居民储蓄行为中起着重要作用.本文基于理性消费者最大化其一生效用的假设,推导出衡量居民预防性储蓄动机强度的新公式.随后,用30个省际地区1985-2010年的年度数据进行实证分析,结果显示,1998年前后城镇居民存在着明显的预防性储蓄强度的结构变化,这种转变对于政府决策具有重要意义.     

Generalizing the permanent-income hypothesis: Revisiting Friedman's conjecture on consumption

Friedman's contribution to the consumption literature goes well beyond the seminal permanent-income hypothesis. He conjectured that the marginal propensity to consume out of financial wealth shall be larger than out of “human wealth”, the present discounted value of future labor income. I present an explicitly solved model to deliver this widely noted consumption property by specifying that the conditional variance of changes in income increases with its level. A larger realization of income not only implies a higher level of human wealth, but also signals a riskier stream of future labor income, inducing a higher precautionary saving, and thus giving rise to Friedman's conjecture. Appropriately adjusting human wealth for income risk, I show that Friedman's conjecture may be formulated as a “generalized” permanent income hypothesis. I further show that Friedman's conjecture captures the first-order effect of stochastic precautionary savings. Finally, I propose a natural decomposition of the optimal saving rule to formalize various motives for holding wealth as emphasized in [Friedman, M., 1957. A Theory of the Consumption Function. Princeton University Press, Princeton].     

Housing returns,precautionary savings and consumption: Micro evidence from China

We investigate how changes in home prices affect consumption in China via a wealth channel. Examining a panel of 7955 households via fixed effects and instrumental variable methods, we find a marginal propensity to consume out of housing wealth (home-price MPC) that is concentrated on goods consumed for pleasure rather than necessity. This trend is driven by the value of second homes rather than that of primary residences, suggesting a wealth channel. We further examine whether returns on housing investment, including rental income and home appreciation, fund the wealth channel; however, we find little supporting evidence. In contrast, a reduction in health risk increases the home-price MPC, but a reduction in income risk that also relieves precautionary saving motives does not. Our results are robust to alternative data, common-factor progress, expenditure shocks and bequest motives. We contribute by examining second homes, which carry little of the dual nature of housing that primary residences do, to identify a controversial wealth channel, and by studying the relative effects of health and income risks on the wealth channel.     

Changes in risk and the demand for saving

How does risk affect saving? Empirical work typically examines the effects of detectible differences in risk within the data. How these differences affect saving in theoretical models depends on the metric one uses for risk. For labor-income risk, second-degree increases in risk require prudence to induce increased saving demand. However, prudence is not necessary for first-degree risk increases and not sufficient for higher-degree risk increases. For increases in interest-rate risk, a precautionary effect and a substitution effect need to be compared. This paper provides necessary and sufficient conditions on preferences for an Nth-degree change in risk to increase saving.     

Job uncertainty and deep recessions

We study a model where households are subject to uninsurable unemployment risk, price setting is subject to nominal rigidities, and the labor market is characterized by matching frictions and inflexible wages. Higher risk of job loss and worsening job finding prospects during unemployment depress goods demand because of a precautionary savings motive. Lower goods demand reduces job vacancies and the job finding rate producing an amplification mechanism due to endogenous countercyclical income risk. Amplification derives from the combination of incomplete financial markets and frictional goods and labor markets. The model can account for key features of the Great Recession.     

Insurance demand in the presence of loss-dependent background risk

We analyze insurance demand when insurable losses come with an uninsurable zero-mean background risk that increases in the loss size. If the individual is risk vulnerable, loss-dependent background risk triggers a precautionary insurance motive and increases optimal insurance demand. Prudence alone is sufficient for insurance demand to increase in two cases: the case of fair insurance and the case where the smallest possible loss exceeds a certain threshold value (referred to as the large loss case). We derive conditions under which insurance demand increases or decreases in initial wealth. In the large loss case, prudence determines whether changes in the background risk lead to more insurance demand. We generalize this result to arbitrary loss distributions and find conditions based on decreasing third-degree Ross risk aversion, Arrow–Pratt risk aversion, and Arrow–Pratt temperance.     

Optimal consumption and asset allocation with unknown income growth

Recent empirical evidence supports the view that the income process has an individual-specific growth rate component [Baker, M., 1997. Growth-rate heterogeneity and the covariance structure of life-cycle earnings. Journal of Labor Economics 15, 338-375; Guvenen, F., 2007b. Learning your earning: Are labor income shocks really very persistent? American Economic Review 97, 687-712; Huggett, M., Ventura, G., Yaron, A., 2007. Sources of life-cycle inequality. Working paper, University of Pennsylvania]. Moreover, the individual-specific growth component may be stochastic. Motivated by these empirical observations, I study an individual's optimal consumption-saving and portfolio choice problem when he does not observe his income growth. As in standard income fluctuation problems, the individual cannot fully insure himself against income shocks. In addition to the standard income-risk-induced precautionary saving demand, the individual also has learning-induced precautionary saving demand, which is greater when belief is more uncertain. With constant unobserved income growth, changes in belief are not predictable. However, with stationary stochastic income growth, belief is no longer a martingale. Mean reversion of belief reduces hedging demand on average and in turn mitigates the impact of estimation risk on consumption-saving and portfolio decisions.     

Precautionary Effort: A New Look

While the concept of precautionary saving is well documented, that of precautionary effort has received relatively limited attention. In this note, we set up a two period model in order to analyze the conditions under which the introduction (or deterioration) of an independent background risk increases effort.     

Corporate precautionary cash holdings

This paper models the precautionary motive for a firm's cash holdings. A two-period investment model shows that the cash holdings of financially constrained firms are sensitive to cash flow volatility because financial constraints create an intertemporal trade-off between current and future investments. When future cash flow risk cannot be fully diversifiable, this intertemporal trade-off gives constrained firms the incentives of precautionary savings: they increase their cash holdings in response to increases in cash flow volatility. However, there is no systematic relationship between cash holdings and cash flow volatility for unconstrained firms. We test the empirical implications of our theory using quarterly information from a sample of U.S. publicly traded companies from 1997 to 2002, and find that the empirical evidence supports our theory.     

Buffer stocks and precautionary savings with loss aversion

This paper reexamines buffer stocks and precautionary savings in the presence of loss aversion. We assume that agents are disappointment averse, as in Gul [Econometrica, 59 (1991) 667–686]. We show that the concavity of the marginal utility continues to determine precautionary saving, but its effect is of a second order magnitude (proportional to the square of the coefficient of variation) compared to the first order effect (proportional to the coefficient of variation) induced by loss aversion. We show that a stabilization fund that is rather small when agents are maximizing the conventional expected utility, turns out to be rather large with loss aversion.     

The Explanatory Power and the Forecast Performance of Consumer Confidence Indices for Private Consumption Growth in Turkey

In this study, we assess empirically whether consumer confidence indices contain information about future private consumption growth in Turkey. To this end, we estimate models for quarterly total, durable, and nondurable consumption growth with and without sentiment indicators. We evaluate in-sample forecasts and one-step-ahead out-of-sample forecasts from recursive ordinary least squares (OLS) estimates. We also test permanent income and precautionary savings hypotheses with our results. We use overall indices of CNBC-e and Turkstat-CBRT Surveys, and Consumer Expectations Index (CEI) and Propensity to Consume Index (PCI) from the CNBC-e Survey as sentiment measures. We show that the lagged values of consumer sentiment have explanatory power on consumption growth. However, when used in conjunction with other economic variables such as real labor income, real stock price, real interest rate, and exchange rate, only CNBC-e for total consumption, and CBRT and PCI for nondurable consumption provide independent information about future consumption growth. Similarly, the gains in out-of-sample forecasts are observed under the absence of other variables and disappear in almost all cases following their inclusion to the estimations. Finally, we find no clear evidence for either precautionary savings motive or permanent income hypothesis on the link between consumer sentiment and future total consumption changes.     

金融摩擦、收入风险与财富不平等

本文通过构建带有职业选择的两部门异质模型,探讨了个体面临的金融摩擦和收入风险对财富分配的作用机制。结果发现,经济中存在的金融摩擦会通过职业选择、自我保险和自融资来影响个人的财富积累,从而导致财富的集中和不平等。对模型模拟的结果表明:降低金融摩擦在总体上会降低财富不平等程度,但对不同财富阶层的影响不同,其在大幅减少前1%和前10%阶层财富份额的同时,虽然也会在一定程度上提升后50%阶层的财富份额,但提升幅度并不大,过高或过低的企业家收入风险,都会加大财富不平等程度,因而存在一个使经济中财富不平等程度最低的适度企业家收入风险水平;虽然金融摩擦和收入风险都会影响经济中的财富不平等,但收入风险本身对财富不平等程度的影响较小,其主要是通过金融摩擦放大了经济中财富不平等的程度。     

When does uncovered interest parity hold?

A consensus is emerging that returns to the currency carry trade are driven by two factors. One of these is probably consumption risk but there is widespread disagreement about the identity of the remaining factor. This paper bolsters the case for volatility being the unknown factor. A structural model that specifies that monetary volatility is the second factor is tested for 56 monetary regimes using the artificial economy methodology. The negative slope in the Fama regression arises when monetary volatility is low and the precautionary savings motive dominates the intertemporal substitution motive. When monetary volatility is high, the Fama slope is positive in line with uncovered interest parity. We conclude that, given the predominance of precautionary savings, the degree of monetary volatility explains whether uncovered interest parity holds.     

The Time‐Varying Volatility of Earnings and Aggregate Consumption Growth

Time‐varying specifications for the conditional variance of earnings of U.S. households are estimated with micro data over the period 1968–92. The cross‐sectional mean of the estimated time‐varying uncertainty of individual households has a significant impact on aggregate consumption growth. As such, aggregate precautionary savings may be more important than what is suggested by the results of estimating standard regression equations for aggregate consumption growth that incorporate only lagged income growth and the real interest rate. The estimation of a buffer stock consumption model with time‐varying earnings uncertainty suggests that the precautionary savings motive is cyclical and has become less important in the 1980s.