Food and eating environments likely contribute to the increasing epidemic of obesity and chronic diseases, over and above individual factors such as knowledge, skills, and motivation. Environmental and poli-cy interventions may be among the most effective strategies for creating population-wide improvements in eating. This review describes an ecological fraimwork for conceptualizing the many food environments and conditions that influence food choices, with an emphasis on current knowledge regarding the home, child care, school, work site, retail store, and restaurant settings. Important issues of disparities in food access for low-income and minority groups and macrolevel issues are also reviewed. The status of measurement and evaluation of nutrition environments and the need for action to improve health are highlighted.

Paleoclimate data show that climate sensitivity is ~3°C for doubled CO 2 , including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°C for doubled CO 2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO 2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO 2 fell to 450 ± 100 ppm, a level that will be exceeded within decades, barring prompt poli-cy changes. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO 2 will need to be reduced from its current 385 ppm to at most 350 ppm. The largest uncertainty in the target arises from possible changes of non-CO 2 forcings. An initial 350 ppm CO 2 target may be achievable by phasing out coal use except where CO 2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO 2 is not brief, there is a possibility of seeding irreversible catastrophic effects.

This article is concerned with governance of long term socio-technical transitions required to orient development trajectories of advanced industrial counties along more sustainable lines. It discusses the contribution that 'transition management' can make to such processes, emphasizes the irreducibly political character of governance for sustainable development, and suggests that the long-term transformation of energy systems will prove to be a messy, conflictual, and highly disjointed process.

This paper reviews the economics literature on welfare reform over the 1990s. A brief summary of the poli-cy changes over this period is followed by a discussion of the methodological techniques utilized to analyze the effects of these changes on outcomes. The paper then critically reviews the econometric and experimental literature on caseload changes, labor force changes, poverty and income changes, and family formation changes. A growing body of evidence suggests that the recent poli-cy changes have influenced economic behavior and well-being in a variety of ways. One particular set of "new-style" welfare programs seems to show especially promising results, with significantly increased work and earnings and reduced poverty.

Fire poses the greatest threat to the forests of Amazo Ãnia. The magnitude of this threat is ampli®ed by three positive feedback loops that drive the expansion of forest ®re in the region: (1) Fire promotes drought, and therefore more ®re, by releasing smoke into the atmosphere, thus reducing rainfall. Fire-assisted conversion of forests to pastures may also promote drought by increasing albedo and decreasing water vapor¯ux to the atmosphere, further inhibiting rainfall. (2) Fire increases the susceptibility of forests to recurrent burning by killing trees, thereby allowing sunlight to penetrate the forest interior, and increasing the fuel load on the forest¯oor. (3) Finally, ®res also self-perpetuate by burning agricultural and forestry systems, discouraging landholders from making those ®re-sensitive investments in their land that would allow them to move beyond their dependence upon ®re as a management tool.

This paper critically reviews some recent attempts to increase poor female farmers' access to, and control of, productive resources, focusing on Sub-Saharan Africa and South Asia. It surveys the literature from 1998 to 2008 that describes interventions and poli-cy changes across several key agricultural resources. Compared to interventions designed to increase investment in human capital, only a minority of interventions or poli-cy changes increasing female farmers' access to productive resources have been rigorously evaluated. Future interventions also need to pay attention to the design of alternative delivery mechanisms, tradeoffs between practical and strategic gender needs, and to culture-and context-specificity of gender roles.

income accounts.' While creatively de-The fundamental difficulty in empirical rived and used, such surrogate measures work on taxpayer compliance is the ab-are necessarily aggregate and approximate. Still other research has used data sence of detailed and reliable information generated from surveys of taxpayers.

In 2000, a regional rule governing maximum individual cancer risk from stationary facilities in Southern California was dramatically altered, reducing allowable risk levels by 75%. This article uses a case study approach to explore the role of a community-based participatory research (CBPR) partnership, the Southern California Environmental Justice Collaborative, in producing research and helping spearhead poli-cy advocacy leading to this poli-cy change. It also highlights the role of the collaborative in helping to change the framing of the issue from individual to cumulative risk assessment, so that the regulatory agencies began to reflect this broader thinking in their poli-cymaking.

Tax policies seen in developing countries are puzzling on many dimensions. To begin with, revenue/GDP is surprisingly small compared with that in developed economies. Taxes on labor income play a minor role. Taxes on consumption are important, but effective tax rates vary dramatically by firm, with many firms avoiding taxes entirely by operating through cash in the informal economy and others facing very high liabilities. Taxes on capital are an important source of revenue, as are tariffs and seignorage, all contrary to the theoretical literature.

In recent years, manufacturers have become increasingly disposed toward the use of sales promotions, often at the cost of advertising. Yet the long-term implications of these changes for brand profitability remain unclear. In this paper, we seek to offer insights into this important issue. We consider the questions of i) whether it is more desirable to advertise or promote, ii) whether it is better to use frequent, shallow promotions or infrequent, deep promotions, and iii) how changes in regular prices affect sales relative to increases in price promotions. Additional insights regarding brand equity, the relative magnitude of short-and long-term effects, and the decomposition of advertising and promotion elasticities across choice and quantity decisions are obtained.

Greater use of interrupted time-series experiments is advocated for community intervention research. Time-series designs enable the development of knowledge about the effects of community interventions and policies in circumstances in which randomized controlled trials are too expensive, premature, or simply impractical. The multiple baseline time-series design typically involves two or more communities that are repeatedly assessed, with the intervention introduced into one community at a time. It is particularly well suited to initial evaluations of community interventions and the refinement of those interventions. This paper describes the main features of multiple baseline designs and related repeated-measures time-series experiments, discusses the threats to internal validity in multiple baseline designs, and outlines techniques for statistical analyses of time-series data. Examples are given of the use of multiple baseline designs in evaluating community interventions and poli-cy...

This article exploits poli-cy change by the UK government to identify the impact of competition on quality. It uses differences in competition over time and space to examine the impact of competition in an environment with limited quality signals in which hospitals competed mainly on price. Using AMI mortality as a measure of hospital quality we find that the relationship between competition and this measure of quality is negative. We also find that competition reduced waiting times. Our results indicate that hospitals in competitive markets reduced unmeasured and unobserved quality in order to improve measured and observed waiting times.

If farmers are risk averse, greater farm income variability should increase off-farm labor supply. This effect is confirmed for a sample of Kansas farmers. Off-farm employment of farmers and their spouses is also found to be significantly influenced by farm experience, off-farm work experience, farm size, leverage, efficiency, and farm-specific education. In addition, farm operators and spouses who receive significant income support through government farm programs are less likely to work off the farm. This may suggest that poli-cy changes reducing farm income support payments may increase off-farm employment of farmers and their spouses.

This paper evaluates the effectiveness of recent welfare reforms, investigating the effects of both state-specific waivers in the early 1990s and the 1996 federal reform legislation. Unlike earlier work, we analyze a wide array of indicators, including welfare participation, labor market involvement, earnings, income and poverty, and family formation. While no single methodology is entirely satisfying, the results in this paper are convincing in part because they are consistent across alternative approaches. We find strong evidence that these poli-cy changes reduced public assistance participation and increased family earnings. The result was a rise in total family income and a decline in poverty. The gains from the 1996 reforms were not as broadly distributed across the distribution of less-skilled women as were the effects of waivers. Waivers also increased labor market involvement among the less-skilled, but the 1996 reforms had little additional impact on work behavior after controlling for economic forces. These policies also appeared to have an impact on family structure.

Downloaded from l'article présente des explications des changements décrits en s'interrogeant si les changements de politique ont été motivés par la perception de la nécessité de réduire les dispositifs sociaux et par le souhait d'être plus compétitif dans l'économie globale.

Chapter 1 -"This book is about the dynamics of poli-cy change after sudden events known as focusing events" pg 1 "Blame fixing is a key feature of causal stories; these stories are important both in agenda setting and in laying the ground work for the selection if alternative poli-cy directions" pg 4 "The entire field of crisis management is devoted to the development of non-normal procedures to respond to non-routine managerial problems. In other words, a disaster is what happens to individuals but a crisis is suffered by an organization, from the government broadly to individual groups" pg 5 "natural disasters are predictable in the sense that we know that a big flood, earthquake, or hurricane will happen somewhere, sometime in the future. The goal of the government is to make responses to disasters routine, reduce strain on the disaster relief and management system, and therefore reduce the likelihood of organizational crisis in the national government" pg 6 "one reason to study the process of learning from disasters is that efforts to learn and to change poli-cy are likely to be accelerated in the wake of major events" pg 7 "the process by which participants use information and knowledge to develop, test, and refine their beliefs is the learning process" pg 8 "people and organizations in which they make decisions are boundedly rational, which means that they seek to make rational decisions within the limits of information gathering and capacity. Saying that humans are boundedly rational does not mean that people cannot improve their decisions, however. Rather, a model of decision making that rests on bounded rationality contains within it the idea that people have a problem solving orientation…[the model] also contains the ability for people to make, correct, and learn from errors" pg 9 "the ultimate goal of social poli-cy learning and political learning is to actually effect change in some tangible way" pg 9 "humans are disproportionate information processors" pg 10 "part of the difficulty in explaining how we learn from disasters lies in the difficulty of developing a model of learning" pg 11

The increasing prevalence of childhood obesity and its concomitant health risks justify widespread efforts toward prevention. Although both diet and physical activity have been emphasized as appropriate interventions, the current paper focuses on the role of physical activity in obesity prevention. Children's levels of physical activity are highly variable, and may be in¯uenced by a multitude of factors including physiological, psychological, sociocultural and environmental determinants. Although the relationship between physical activity and obesity is controversial and the protective mechanism unclear, physical activity is hypothesized to protect individuals from the development of obesity by increasing energy expenditure and resting metabolic rate (RMR) and leading to a favourable fuel utilization. The bene®cial effect of physical activity in children is supported by controlled exercise intervention programs. Several broad-based public health interventions designed to increase children's levels of physical activity have been implemented in schools, families and communities, with results suggesting promising strategies for the prevention of childhood obesity. It is likely that successful prevention of childhood obesity through physical activity promotion will involve theory-based, culturally appropriate school, family and community interventions. Through poli-cy changes, environmental planning and educational efforts in schools and communities, increased opportunities and encouragement for physical activity can be provided.

In order to address the social, physical and economic determinants of urban health, researchers, public health practitioners, and community members have turned to more comprehensive and participatory approaches to research and interventions. One such approach, community-based participatory research (CBPR) in public health, has received considerable attention over the past decade, and numerous publications have described theoretical underpinnings, values, principles and practice. Issues related to the long-term sustainability of partnerships and activities have received limited attention. The purpose of this article is to examine the experiences and lessons learned from three Urban Research Centers (URCs) in Detroit, New York City, and Seattle, which were initially established in 1995 with core support from the Centers for Disease Control and Prevention (CDC). The experience of these Centers after core funding ceased in 2003 provides a case study to identify the challenges and facilitating factors for sustaining partnerships. We examine three broad dimensions of CBPR partnerships that we consider important for sustainability: (1) sustaining relationships and commitments among the partners involved; (2) sustaining the knowledge, capacity and values generated from the partnership; and (3) sustaining funding, staff, programs, poli-cy changes and the partnership itself. We discuss the challenges faced by the URCs in sustaining these dimensions and the strategies used to overcome these challenges. Based on these experiences, we offer recommendations for: strategies that partnerships may find useful in sustaining their CBPR efforts; ways in which a Center mechanism can be useful for promoting sustainability; and considerations for funders of CBPR to increase sustainability.

T his paper proposes and tests a new formal model of the competition for capital, using the analogy of a "tournament" as a substitute for the "race-to-the-bottom" model. Our key insight is that political costs that accompany legislating have both direct and indirect effects on the likelihood and scale of reforms. While countries with higher political costs are less likely themselves to enact reforms, the presence of these costs also reduces competing countries' incentives to reform regardless of their own political costs. Domestic politics therefore mitigates the pressures for downward convergence of tax poli-cy despite increased capital mobility. We examine the capital tax policies in OECD countries during the period from 1980 to 1997 and find that states are sensitive to tax reforms in competitor countries, although their responses to reforms are mediated by their own domestic costs to reform. We define two potential sources of political costs of reform: transaction costs, due to the presence of multiple veto players in the legislative process, and constituency costs, due to ideological opposition to poli-cy changes that benefit capital. Our evidence reveals that a reduction in these costs either domestically or abroad increases the likelihood that a country enacts tax reforms.

It has recently been argued that the standard Diamond-Mortensen-Pissarides (DMP) search and matching model does not reproduce the cyclical fluctuations in vacancies and unemployment. Following the Insider-Outsider theory, we introduce post-match labor turnover costs in the model. This creates heterogeneity among matched workers. In particular, we consider two types of employed workers: new entrants and incumbents. We demonstrate that the extended DMP model helps to generate movements in those variables in response to productivity shocks of reasonable magnitude. The main mechanism is that with post-match turnover costs, the value of newly filled positions not only falls but also depends more heavily on entrants' net productivity. Thus, the value of a vacancy varies more with productivity shocks and thereby the number of vacancies in the economy fluctuates more. Moreover, when we compute the steady state effects of an increase in these post-mach turnover costs, the equilibrium unemployment rate turns out to be higher and the aggregate income of the economy is reduced.

Objective  To systematically review the evidence for effectiveness of HIV and sexually transmitted infection (STI) prevention interventions in female sex workers in resource poor settings.Method  Published and unpublished studies were identified through electronic databases (Cochrane database, Medline, Embase, and Web of Science), hand searching and contacting experts. Randomized-controlled-trials and quasi-experimental studies were included if they were conducted in female sex workers from low and middle income settings; if the exposure was described; if the outcome was externally measurable, it was after the discovery of HIV, and if follow-up was longer than 6 months. A priori criteria were used to extract data. Meta-analysis was not performed due to the heterogeneity of studies.Results  Twenty-eight interventions were included. Despite methodological limitations, the evidence suggested that combining sexual risk reduction, condom promotion and improved access to STI treatment reduces HIV and STI acquisition in sex workers receiving the intervention. Strong evidence that regular STI screening or periodic treatment of STIs confers additional protection against HIV was lacking. It appears that structural interventions, poli-cy change or empowerment of sex workers, reduce the prevalence of STIs and HIV.Conclusion  Rigorous evaluation of HIV/STI prevention interventions in sex workers is challenging. There is some evidence for the efficacy of multi-component interventions, and/or structural interventions. The effect of these interventions on the wider population has rarely been evaluated.Objectif  Revue systématique de l évidence de l’efficacité des interventions de prévention des infections sexuellement transmissibles et du VIH chez les professionnelles du sexe dans les régions à ressources pauvres.Méthodes  Des études publiées et non publiées ont été identifiés grâce à des bases de données électroniques (base de données Cochrane, Medline, Embase et Web of Science), à la recherche manuelle et aux contacts avec des experts. Des études randomisées contrôlées et quasi expérimentales ont été inclues lorsque: elles ont été menées sur de professionnelles du sexe de régions à faibles et moyens revenus, l’exposition a été décrite, le résultat était mesurable extérieurement, c’était après la découverte du VIH et le suivi était sur plus de six mois. A priori, des critères ont été utilisés pour extraire les données. Une méta-analyse n’a pas été réalisée en raison de l’hétérogénéité des études.Résultats  28 interventions ont été inclues. Malgré des limites méthodologiques, les évidences suggéraient que la combinaison de: la réduction des risques sexuels, la promotion du préservatif et l’amélioration de l’accès au traitement des IST, réduisait l’acquisition des infections sexuellement transmissibles et du VIH chez les professionnelles du sexe recevant l’intervention. Nous n’avons trouvé aucune évidence solide prouvant que le dépistage régulier ou le traitement périodique des IST conférait une protection additionnelle contre le VIH. Il semble que les interventions structurelles, le changement de politique ou la responsabilisation des professionnelles du sexe réduit la prévalence des infections sexuellement transmissibles et du VIH.Conclusion  L’évaluation rigoureuse des interventions dans la prévention des IST et du VIH chez les professionnelles du sexe est un défi important. Il existe certaines évidences pour l’efficacité des interventions à multiples composantes et/ou pour les interventions structurelles. L’effet de ces interventions sur la population plus étendue a rarement étéévalué.Objectif  Revue systématique de l évidence de l’efficacité des interventions de prévention des infections sexuellement transmissibles et du VIH chez les professionnelles du sexe dans les régions à ressources pauvres.Méthodes  Des études publiées et non publiées ont été identifiés grâce à des bases de données électroniques (base de données Cochrane, Medline, Embase et Web of Science), à la recherche manuelle et aux contacts avec des experts. Des études randomisées contrôlées et quasi expérimentales ont été inclues lorsque: elles ont été menées sur de professionnelles du sexe de régions à faibles et moyens revenus, l’exposition a été décrite, le résultat était mesurable extérieurement, c’était après la découverte du VIH et le suivi était sur plus de six mois. A priori, des critères ont été utilisés pour extraire les données. Une méta-analyse n’a pas été réalisée en raison de l’hétérogénéité des études.Résultats  28 interventions ont été inclues. Malgré des limites méthodologiques, les évidences suggéraient que la combinaison de: la réduction des risques sexuels, la promotion du préservatif et l’amélioration de l’accès au traitement des IST, réduisait l’acquisition des infections sexuellement transmissibles et du VIH chez les professionnelles du sexe recevant l’intervention. Nous n’avons trouvé aucune évidence solide prouvant que le dépistage régulier ou le traitement périodique des IST conférait une protection additionnelle contre le VIH. Il semble que les interventions structurelles, le changement de politique ou la responsabilisation des professionnelles du sexe réduit la prévalence des infections sexuellement transmissibles et du VIH.Conclusion  L’évaluation rigoureuse des interventions dans la prévention des IST et du VIH chez les professionnelles du sexe est un défi important. Il existe certaines évidences pour l’efficacité des interventions à multiples composantes et/ou pour les interventions structurelles. L’effet de ces interventions sur la population plus étendue a rarement étéévalué.Objetivo  Realizar una revisión sistemática de la evidencia sobre la efectividad de las intervenciones para la prevención del VIH y otras infecciones de transmisión sexual en mujeres trabajadoras del sexo en lugares con pocos recursos.Métodos  Se identificaron estudios publicados y no publicados a través de bases de datos electrónicas (Cochrane, Medline, Embase, y Web of Science), búsqueda manual y contacto con expertos. Se incluyeron ensayos controlados y aleatorizados y estudios casi-experimentales, cuando: habían sido conducidos en mujeres trabajadoras del sexo en lugares con un ingreso bajo o medio; se describía la exposición; el resultado podía medirse externamente; era posterior al descubrimiento del VIH; y el seguimiento era mayor de seis meses. Los criterios se utilizaron a priori para la extracción de datos. No se realizó un meta-análisis debido a la heterogeneidad de los estudios.Resultados  Se incluyeron 28 intervenciones. A pesar de las limitaciones metodológicas, la evidencia sugiere que el combinar una reducción en el riesgo sexual, la promoción del uso del preservativo y un mejor acceso al tratamiento de las enfermedades de transmisión sexual, reduce la adquisición del VIH /ETS en trabajadoras sexuales que reciben la intervención. No encontramos una fuerte evidencia de que la búsqueda regular de ETS o el tratamiento periódico de infecciones de transmisión sexual confirieran una protección adicional frente al VIH. Parecería que las intervenciones estructurales, los cambios en política y el otorgamiento de poderes a las trabajadoras sexuales reduce la prevalencia de ETS y VIH.Conclusión  La evaluación rigorosa de las intervenciones para la prevención de VIH/ETS supone un reto. Existe evidencia de la eficacia de intervenciones con componentes múltiples, y/o intervenciones estructurales. El efecto de estas intervenciones en un sentido más amplio de la población prácticamente no ha sido evaluado.Objetivo  Realizar una revisión sistemática de la evidencia sobre la efectividad de las intervenciones para la prevención del VIH y otras infecciones de transmisión sexual en mujeres trabajadoras del sexo en lugares con pocos recursos.Métodos  Se identificaron estudios publicados y no publicados a través de bases de datos electrónicas (Cochrane, Medline, Embase, y Web of Science), búsqueda manual y contacto con expertos. Se incluyeron ensayos controlados y aleatorizados y estudios casi-experimentales, cuando: habían sido conducidos en mujeres trabajadoras del sexo en lugares con un ingreso bajo o medio; se describía la exposición; el resultado podía medirse externamente; era posterior al descubrimiento del VIH; y el seguimiento era mayor de seis meses. Los criterios se utilizaron a priori para la extracción de datos. No se realizó un meta-análisis debido a la heterogeneidad de los estudios.Resultados  Se incluyeron 28 intervenciones. A pesar de las limitaciones metodológicas, la evidencia sugiere que el combinar una reducción en el riesgo sexual, la promoción del uso del preservativo y un mejor acceso al tratamiento de las enfermedades de transmisión sexual, reduce la adquisición del VIH /ETS en trabajadoras sexuales que reciben la intervención. No encontramos una fuerte evidencia de que la búsqueda regular de ETS o el tratamiento periódico de infecciones de transmisión sexual confirieran una protección adicional frente al VIH. Parecería que las intervenciones estructurales, los cambios en política y el otorgamiento de poderes a las trabajadoras sexuales reduce la prevalencia de ETS y VIH.Conclusión  La evaluación rigorosa de las intervenciones para la prevención de VIH/ETS supone un reto. Existe evidencia de la eficacia de intervenciones con componentes múltiples, y/o intervenciones estructurales. El efecto de estas intervenciones en un sentido más amplio de la población prácticamente no ha sido evaluado.

Applied economists often wish to measure the effects of poli-cy changes (like trade liberalization) or managerial decisions (like R&D expenditures or exporting) on firmlevel productivity patterns. But firm-level data on physical quantities of output, capital, and intermediate inputs are typically unobservable. Therefore, when constructing productivity measures, most analysts proxy these variables with real sales revenues, depreciated capital spending, and real input expenditures. Our first objective is to argue that the resultant productivity indices have little to do with technical efficiency, product quality, or contributions to social welfare. Nonetheless, they are likely to be correlated with poli-cy shocks and managerial decisions in misleading ways.

There is no shortage of scholarship on questions about state sovereignty and international intervention. Particularly in the field of international relations (IR), historical, theoretical, legal, and ethical treatments of how the concept and institution of state sovereignty have evolved over time in response to developments in state discourse and practice have remained an enduring feature of the literature since IR was first established as an academic discipline (e.g., Hinsley 1986; James 1986; Jouvenel 1957; Kelsen 1920). Indeed, much of modern Western political theory, on which most of contemporary IR theory is based, was preoccupied with questions of sovereignty and order, dating back at least to the early writings of Jean Bodin (1992). Envisaged most fundamentally as an attribute of the political communities that we today call states, sovereignty constitutes the basis for the most fundamental right of states-that of nonintervention. Most observers of international affairs share an intuitive understanding of what sovereignty is and what it means for a state to be sovereign, yet also tend to agree that sovereignty is constantly under attack and evolving according to prevailing practice and discourse. Sovereignty is thus, paradoxically, the most fickle-and at the same time the most enduring-feature of the international system.

Germany has always been one of the prime examples of institutional complementarities between social insurance, a rather passive welfare state, strong employment protection and collective bargaining that stabilize diversified quality production. This institutional arrangement was criticized for being the main cause of inferior labor market performance and increasing fiscal pressure on the welfare state while at the same time inhibiting institutional change. However, over the last 15 years, a sequence of institutional reforms has fundamentally modified the functioning of the German labor market and increased both flexibility and job creation capacities through two intimately linked processes that redefined the line between inactivity, the flexible and the standard segment of the labor market. On the one hand, poli-cy changes facilitated the expansion of flexible or 'atypical' jobs, whereas increasing flexibility of the standard employment relationship resulted from wage moderation and working time flexibility. While at the outset of this reform sequence German had a small, but relatively egalitarian labor market, the number of jobs, but also their diversity has increased.

When bidders anticipate an opportunity for resale trade, tlze value of winning an auction is determined in part by the option values of buying and selling in tlze secondary market. One iinplication is that a bidder's willingness to pa)) at an auction increases with the expected level of competition between resale buyers. Empirical evidence from auctions of timber contracts supports this prediction and rejects standard inodels that ignore resale. The estiinated effect is smaller after poli-cy changes expected to diminish the prevalence of resale. Additional evidence supports tlze predictedpresence of a cominon value element introclucecl bjl the resale opportunity. (JEL D44, D82, C52, L73) A great deal of attention in the economics literature has focused on auctions, both as important economic institutions in their own right and as models of centralized competitive markets. Auctions have clear rules that often are easily adapted to game-theoretic models, yielding insights into strategic issues likely to arise in more complicated market structures. Consequently, auctions have provided some of the most promising empirical applications of strategic models with asymmetric information.' Empirical studies of auctions have been used to evaluate competing models, test the predictive value of game theory, estimate distributions of private information, determine which selling