Mark Huggett

Understanding Why High Income Households Save More Than Low Income Households

This paper investigates why high income households in the United States save on average more than low income households in cross-section data. The three explanations considered are (1) age differences across households, (2) temporary earnings shocks, and (3) the structure of transfer payments. We use a calibrated life-cycle model to evaluate the quantitative importance of these explanations and find that age and the structure of transfers are quantitatively important in producing the cross-section pattern of United States savings rates. Temporary shocks are of secondary importance.

Does productivity growth fall after the adoption of new technology

Abstract A number of theoretical models of technology adoption have been proposed that imply that measured productivity growth may initially fall and then later rise after the adoption of a new technology. This paper investigates whether or not this implication is a feature of plant-level data from the Colombian manufacturing sector. We focus on technology adoption embodied in new equipment. We find evidence that the effect of a large equipment purchase is initially to reduce plant-level total factor productivity growth.

How Well Does the U.S. Social Insurance System Provide Social Insurance

We analyze the insurance provided by the U.S. social security and income tax system within a model in which agents receive idiosyncratic, wage rate shocks that are privately observed. We consider two reforms: a piecemeal reform that optimally chooses the social security benefit function and a radical reform that eliminates the entire social insurance system and replaces it with an optimal tax on lifetime earnings. The radical reform outperforms the piecemeal reform and achieves nearly all of the maximum possible welfare gain when wages differ permanently over the lifetime. When wage shocks match properties in U.S. data, the piecemeal reform outperforms the radical reform.

Aggregate precautionary savings: when is the third derivative irrelevant?

When does idiosyncratic earnings uncertainty increase aggregate saving? We address this question in the context of a general equilibrium model where infinitely-lived agents receive idiosyncratic labor endowment shocks, hold a risk-free asset to smooth consumption and face a liquidity constraint. We prove that the steady-state capital stock is always larger in any equilibrium with idiosyncratic shocks and a liquidity constraint than without idiosyncratic shocks (i.e. there is aggregate precautionary saving) as long as utility functions are strictly concave. We also prove that aggregate precautionary saving occurs if and only if the liquidity constraint binds for some agents.

Taxing Top Earners: A Human Capital Perspective

We analyze the Diamond-Saez policy recommendation within a human capital model. We calculate the steady-state welfare implications of raising the marginal income tax rate on top incomes from current levels to those in the range of 54 percent to 80 percent. We also calculate the transitional dynamics implied by such a modification of the US tax system.

When Are Comparative Dynamics Monotone

A common problem in dynamic economic theory is to determine when an increase in a parameter and/or an initial condition increases the future dynamics of a theoretical economy. This paper provides conditions that are necessary and sufficient for making statements of this type. The result is applicable to situations with a single agent or with many agents in the presence or absence of uncertainty. The result holds for general notions of what it means for a parameter, an initial condition or even the dynamics of a model to be increasing.

Human capital values and returns: Bounds implied by earnings and asset returns data

We provide theory for calculating bounds on both the value of an individual[modifier letter apostrophe]s human capital and the return on an individual[modifier letter apostrophe]s human capital, given knowledge of the process governing earnings and financial asset returns. We calculate bounds using U.S. data on male earnings and financial asset returns. The large idiosyncratic component of earnings risk implies that bounds on values and returns are quite loose. However, when aggregate shocks are the only source of earnings risk, both bounds are tight.

Interpreting Life-Cycle Inequality Patterns as an Efficient Allocation: Mission Impossible?

Data on consumption, earnings, wages and hours dispersion over the life cycle has been viewed as being at odds with an efficient allocation. We challenge this view. We show that a model with preference and wage shocks and full insurance produces the type of inequality patterns across age groups found in U.S. data. The efficient allocation model requires an increasing preference shifter dispersion profile to account for an increasing consumption dispersion profile. We examine U.S. data and find support for the view that the dispersion in preference shifters increases with age.

The Money Value of a Man

This paper posits a notion of the value of an individual’s human capital and the associated return on human capital. These concepts are examined using U.S. data on male earnings and financial asset returns. We decompose the value of human capital into a bond, a stock and a residual value component. We find that (1) the bond component of human capital is larger than the stock component at all ages, (2) the value of human capital is far below the value implied by discounting earnings at the risk-free rate, (3) mean human capital returns exceed stock returns early in life and decline with age and (4) human capital returns and stock returns have a small positive correlation over the working lifetime.

Precautionary wealth accumulation: a positive third derivative is not enough

It is commonly conjectured that expected wealth accumulation increases when earnings risk increases as long as the utility function in each period is increasing, concave and has a positive third derivative. We present a counter example which highlights the importance of the convexity of the savings function.