This paper explores tests of the hypothesis that the tail thickness of a distribution is constant over time. Using Hill's conditional maximum likelihood estimator for the tail index of a distribution, tests of tail shape constancy are constructed that allow for an unknown breakpoint. The recursive test is shown to be inconsistent in one direction, and only a one-sided test is recommended. Specifically, the test can be used when the alternative hypothesis is that the tail index decreases over time. A rolling and sequential version of the test is consistent in both directions. The methods are illustrated on recent stock price data for Thailand, Malaysia and Indonesia. The period covers the recent Asian financial crisis and enables us to assess whether breakpoints in domestic asset return distributions are related to known changes in institutional arrangements in the foreign currency markets of these countries.

With fixed costs of participating in the stock market, consumers with high income will participate in the stock market, but consumers with lower income will not participate. If a fully funded defined-contribution Social Security system tries to exploit the equity premium by selling a dollar of bonds per capita and buying a dollar of equity per capita, consumers who save but do not participate in the stock market will increase their consumption, thereby reducing saving and capital accumulation. Calibration of a general-equilibrium model indicates that this policy could reduce the aggregate capital stock substantially, by about 50 cents per capita.

This paper uses a unique data set to measure peer effects among college roommates. Freshman year roommates and dormmates are randomly assigned at Dartmouth College. I find that peers have an impact on grade point average and on decisions to join social groups such as fraternities. Residential peer effects are markedly absent in other major life decisions such as choice of college major. Peer effects in GPA occur at the individual room level, whereas peer effects in fraternity membership occur both at the room level and the entire dorm level. Overall, the data provide strong evidence for the existence of peer effects in student outcomes.

During 1984–1996, welfare and tax policy were changed to encourage work by single mothers. The Earned Income Tax Credit was expanded, welfare benefits were cut, welfare time limits were added, and welfare cases were terminated. Medicaid for the working poor was expanded, as were training programs and child care. During this same time period there were unprecedented increases in the employment and hours of single mothers. We show that a large share of the increase in work by single mothers can be attributed to the EITC and other tax changes, with smaller shares for welfare benefit cuts, welfare waivers, training programs and child care programs.

This paper makes two contributions to the modeling of addiction. First, we provide new and convincing evidence that smokers are forward-looking in their smoking decisions, using state excise tax increases that have been legislatively enacted but are not yet effective, and monthly data on consumption. Second, we recognize the strong evidence that preferences with respect to smoking are time inconsistent, with individuals both not recognizing the true difficulty of quitting and searching for self-control devices to help them quit. We develop a new model of addictive behavior that takes as its starting point the standard “rational addiction” model, but incorporates time-inconsistent preferences. This model also exhibits forward-looking behavior, but it has strikingly different normative implications; in this case optimal government policy should depend not only on the externalities that smokers impose on others but also on the “internalities” imposed by smokers on themselves. We estimate that the optimal tax per pack of cigarettes should he at least one dollar higher under our formulation than in the rational addiction case.

The study offers the most direct evidence to date on price noises in call auctions and their correction. We examine a unique sample of two identical securities (two equal-payoff Israeli government bonds) that were traded on separate yet almost simultaneous auctions on the Tel-Aviv Stock Exchange (TASE). The prices of the bonds were equal on average. However, on most of the sample days there were price differences between the bonds. Various estimates suggest that the price noise in one bond is practically uncorrelated with that of the other, and both disappear by the end of the next-day auction.

We examine short-run impacts of changes in residential neighborhoods on the well-being of families residing in high-poverty public housing projects who received Section 8 housing vouchers through a random lottery. Households offered vouchers experienced improvements in multiple measures of well-being relative to a control group, including increased safety, improved health among household heads, and fewer behavior problems among boys. There were no significant short-run impacts of vouchers on the employment, earnings, or welfare receipt of household heads. Children in households offered vouchers valid only in low poverty neighborhoods also had reduced likelihood of injuries, asthma attacks, and victimizations by crime.

This paper analyzes the impact of automatic enrollment on 401(k) savings behavior. We have two key findings. First, 401(k) participation is significantly higher under automatic enrollment. Second, a substantial fraction of 401(k) participants hired under automatic enrollment retain both the default contribution rate and fund allocation even though few employees hired before automatic enrollment picked this particular outcome. This “default” behavior appears to result from participant inertia and from employee perceptions of the default as investment advice. These findings have implications for the design of 401(k) savings plans as well as for any type of Social Security reform that includes personal accounts over which individuals have control. They also shed light more generally on the importance of both economic and noneconomic (behavioral) factors in the determination of individual savings behavior.

This study analyzes the relation between auditors' perceived business risk and audit fees to determine whether audit firms or their clients bear the expected legal costs of business risk. We predict that hourly audit fees and the number of audit hours are increasing in business risk. Using confidential survey data collected by a large international accounting firm for 422 audits, we find that high business risk increases the number of audit hours, but not the fee per hour. This implies that firms perceive firm‐level differences in business risk and obtain compensation through billing additional hours, not by raising the hourly charge.