The sharp decline in the stock prices of several firms at which employees held a large fraction of their 401(k) plan assets in company stock, including Enron, Global Crossing, Lucent, and Polaroid, has sparked a public-policy debate about investment options in 401(k) plans. At many large firms, particularly those with retirement saving plans that combine elements of an Employee Stock Ownership Plan (ESOP) with a traditional 401(k), a substantial fraction of defined-contribution retirement-plan assets are held in company stock. Such undiversified holdings are a source of concern because they raise the volatility of the retirement wealth for employees and expose some workers to the prospect of very small retirement values. Holding an undiversified position in employer stock may be particularly costly because of the potential correlation between company stock returns and the value of the worker’s human capital, which may depend on the company’s prospects. This paper reviews the extent of undiversified company-stock investments in 401(k) plans, evaluates the cost of such investments from an employee’s perspective, and discusses a range of policy actions that could address the excessive concentration of retirement plan assets.

Does Aid Matter? Measuring the Effect of Student Aid on College Attendance and Completion by Susan M. Dynarski. Published in volume 93, issue 1, pages 279-288 of American Economic Review, March 2003

This paper explores the effect of discretion in estate valuation techniques on the effective estate tax burden on different asset classes. For some assets, such as liquid securities, there is relatively little discretion in valuation. For other assets, such as partial interests in closely-held businesses, family limited partnerships, and real assets or collectibles that are traded in thin markets, estate valuations may be more difficult to establish. Estate tax filers may therefore be able to select valuations that reduce the reported value of the estate assets, and therefore the effective estate tax burden. In 1998, estates that invoked the doctrine of "minority discounts" in valuing non-controlling interests in limited partnerships claimed an average discount of 36 percent for these assets, relative to their estimated market value. More than half of all limited partnership assets reported on estate tax returns were valued using this doctrine. This suggests that for a given statutory estate tax rate, the effective estate tax burden may be greater on assets that are easily valued than on difficult-tovalue assets. A comparison of the mix of assets reported on estate tax returns, and the mix the estate tax returns would be predicted to hold, given data from the Survey of Consumer Finances, is consistent with lower relative valuations for difficult-to-value assets.

Inference methods that recognize the clustering of individual observations have been available for more than 25 years. Brent Moulton (1990) caught the attention of economists when he demonstrated the serious biases that can result in estimating the effects of aggregate explanatory variables on individual-specific response variables. The source of the downward bias in the usual ordinary least-squares (OLS) standard errors is the presence of an unobserved, state-level effect in the error term. More recently, John Pepper (2002) showed how accounting for multi-level clustering can have dramatic effects on t statistics. While adjusting for clustering is much more common than it was 10 years ago, inference methods robust to cluster correlation are not used routinely across all relevant settings. In this paper, I provide an overview of applications of cluster-sample methods, both to cluster samples and to panel data sets.

A Picture Is Worth a Thousand Symbols: A Sociologist's View of the Economic Pursuit of Truth by Joel M. Podolny. Published in volume 93, issue 2, pages 169-174 of American Economic Review, May 2003

The paper investigates the common dynamic properties of business-cycle fluctuations across countries, regions, and the world. We employ a Bayesian dynamic latent factor model to estimate common components in macroeconomic aggregates (output, consumption, and investment) in a 60-country sample covering seven regions of the world. The results indicate that a common world factor is an important source of volatility for aggregates in most countries, providing evidence for a world business cycle. We find that region-specific factors play only a minor role in explaining fluctuations in economic activity. We also document similarities and differences across regions, countries, and aggregates.

Charitable Bequests and Taxes on Inheritances and Estates: Aggregate Evidence from across States and Time by Jon M. Bakija, William G. Gale and Joel B. Slemrod. Published in volume 93, issue 2, pages 366-370 of American Economic Review, May 2003

Equity market liberalizations are like IPOs, but they are IPOs of a country's stock market rather than of individual firms. Both are endogenous events whose benefits are limited by poor investor protection, agency costs, and information asymmetries. As for stock prices following an IPO, there are legitimate concerns about the efficiency in the period following the liberalization of the stock market returns of countries that liberalize their equity markets. Equity markets of liberalizing countries experience extremely strong performance immediately after the liberalization, but then go through a period of poor performance. This pattern of stock returns is more dramatic for countries with poorer financial development before the liberalization.

Changes in the Distribution of Children's Family Income over the 1990's by Rebecca M. Blank and Robert F. Schoeni. Published in volume 93, issue 2, pages 304-308 of American Economic Review, May 2003

Inviting political scientists to tell economists how they could do better work is an act of disciplinary generosity. The reality is that contemporary political science is a net importer of ideas and methods from other disciplines, and from none more than economics. Indeed, some of the most exciting research in political science in the past 40 years has involved the incorporation of ideas from economics. We have neither the space nor the mandate to summarize that research here, but refer interested readers to Gary J. Miller's (1997) extensive review. Our aim here is to offertwo modest case studies of specific instances of overlap between the interests and research efforts of economists and political scientists. Our first case study focuses on describing and explaining participation in the workforce, the polity, and many other social activities and organizations. Our second case study focuses on the impact of political processes and institutions on macroeconomic policies and performance. In both these instances the work of economists has been quite fruitful—but also, we think, hampered by a characteristic overreliance on standard economic models and methods. However, in both areas, recent developments may point the way toward a more constructive research style combining the theoretical and empirical rigor of economics with a broader and more eclectic approach familiar to political scientists.