Publication: How Adverse Selection Affects the Health Insurance Market
Loading...
Date
2001-03
ISSN
Published
2001-03
Author(s)
Editor(s)
Abstract
Adverse selection can be defined as strategic behavior by the more informed partner in a contract against the interest of the less informed partner(s). In the health insurance field, this manifests itself through healthy people choosing managed care and less healthy people choosing more generous plans. Drawing on theoretical literature on the problem of adverse selection in the health insurance market, the author synthesizes concepts developed piecemeal over more than 20 years, using two examples and revisiting the classical contribution of Rothschild and Stiglitz. He highlights key insights, especially from the literature on "equilibrium refinements" and on the theory of "second best." The government can correct spontaneous market dynamics in the health insurance market by directly subsidizing insurance or through regulation; the two forms of intervention provide different results. Providing partial public insurance, even supplemented by the possibility of opting out, can lead to second-best equilibria. The same result holds as long as the government can subsidize contracts with higher-than-average premium-benefit ratios and can tax contracts with lower-than-average premium-benefit ratios. The author analyzes the following policy options relating to the public provision of insurance: a) Full public insurance. b) Partial public insurance with or without the possibility of acquiring supplementary insurance and with or without the possibility of opting out. In recent plans implemented in Germany and the Netherlands, where competition among several health funds and insurance companies was promoted, a public fund was created to discourage risk screening practices by providing the necessary compensation across riks groups. But only "objective" risk adjusters (such as age, gender, and region) were used to decide which contracts to subsidize. Those criteria alone cannot correct the effects of adverse selection. Regulation can exacerbate the problem of adverse selection and lead to chronic market instability, so certain steps must be taken to prevent risk screening and preserve competition for the market. The author considers the following three policy options for regulating the private insurance market: 1) A standard contract with full coverage. 2) Imposition of a minimum insurance requirement. 3) Imposition of premium rate restrictions.
Link to Data Set
Citation
“Belli, Paolo. 2001. How Adverse Selection Affects the Health Insurance Market. Policy Research Working Paper;No. 2574. © http://hdl.handle.net/10986/19694 License: CC BY 3.0 IGO.”
Associated URLs
Associated content
Other publications in this report series
Publication The Future of Poverty(Washington, DC: World Bank, 2025-07-15)Climate change is increasingly acknowledged as a critical issue with far-reaching socioeconomic implications that extend well beyond environmental concerns. Among the most pressing challenges is its impact on global poverty. This paper projects the potential impacts of unmitigated climate change on global poverty rates between 2023 and 2050. Building on a study that provided a detailed analysis of how temperature changes affect economic productivity, this paper integrates those findings with binned data from 217 countries, sourced from the World Bank’s Poverty and Inequality Platform. By simulating poverty rates and the number of poor under two climate change scenarios, the paper uncovers some alarming trends. One of the primary findings is that the number of people living in extreme poverty worldwide could be nearly doubled due to climate change. In all scenarios, Sub-Saharan Africa is projected to bear the brunt, contributing the largest number of poor people, with estimates ranging between 40.5 million and 73.5 million by 2050. Another significant finding is the disproportionate impact of inequality on poverty. Even small increases in inequality can lead to substantial rises in poverty levels. For instance, if every country’s Gini coefficient increases by just 1 percent between 2022 and 2050, an additional 8.8 million people could be pushed below the international poverty line by 2050. In a more extreme scenario, where every country’s Gini coefficient increases by 10 percent between 2022 and 2050, the number of people falling into poverty could rise by an additional 148.8 million relative to the baseline scenario. These findings underscore the urgent need for comprehensive climate policies that not only mitigate environmental impacts but also address socioeconomic vulnerabilities.Publication Exports, Labor Markets, and the Environment(Washington, DC: World Bank, 2025-07-14)What is the environmental impact of exports? Focusing on 2000–20, this paper combines customs, administrative, and census microdata to estimate employment elasticities with respect to exports. The findings show that municipalities that faced increased exports experienced faster growth in formal employment. The elasticities were 0.25 on impact, peaked at 0.4, and remained positive and significant even 10 years after the shock, pointing to a long and protracted labor market adjustment. In the long run, informal employment responds negatively to export shocks. Using a granular taxonomy for economic activities based on their environmental impact, the paper documents that environmentally risky activities have a larger share of employment than environmentally sustainable ones, and that the relationship between these activities and exports is nuanced. Over the short run, environmentally risky employment responds more strongly to exports relative to environmentally sustainable employment. However, over the long run, this pattern reverses, as the impact of exports on environmentally sustainable employment is more persistent.Publication The Macroeconomic Implications of Climate Change Impacts and Adaptation Options(Washington, DC: World Bank, 2025-05-29)Estimating the macroeconomic implications of climate change impacts and adaptation options is a topic of intense research. This paper presents a framework in the World Bank's macrostructural model to assess climate-related damages. This approach has been used in many Country Climate and Development Reports, a World Bank diagnostic that identifies priorities to ensure continued development in spite of climate change and climate policy objectives. The methodology captures a set of impact channels through which climate change affects the economy by (1) connecting a set of biophysical models to the macroeconomic model and (2) exploring a set of development and climate scenarios. The paper summarizes the results for five countries, highlighting the sources and magnitudes of their vulnerability --- with estimated gross domestic product losses in 2050 exceeding 10 percent of gross domestic product in some countries and scenarios, although only a small set of impact channels is included. The paper also presents estimates of the macroeconomic gains from sector-level adaptation interventions, considering their upfront costs and avoided climate impacts and finding significant net gross domestic product gains from adaptation opportunities identified in the Country Climate and Development Reports. Finally, the paper discusses the limits of current modeling approaches, and their complementarity with empirical approaches based on historical data series. The integrated modeling approach proposed in this paper can inform policymakers as they make proactive decisions on climate change adaptation and resilience.Publication The Asymmetric Bank Distress Amplifier of Recessions(Washington, DC: World Bank, 2025-07-11)One defining feature of financial crises, evident in U.S. and international data, is asymmetric bank distress—concentrated losses on a subset of banks. This paper proposes a model in which shocks to borrowers’ productivity dispersion lead to asymmetric bank losses. The framework exhibits a “bank distress amplifier,” exacerbating economic downturns by causing costly bank failures and raising uncertainty about the solvency of banks, thereby pushing banks to deleverage. Quantitative analysis shows that the bank distress amplifier doubles investment decline and increases the spread by 2.5 times during the Great Recession compared to a standard financial accelerator model. The mechanism helps explain how a seemingly small shock can sometimes trigger a large crisis.Publication Impact of Heat Waves on Learning Outcomes and the Role of Conditional Cash Transfers(Washington, DC: World Bank, 2025-07-14)This paper evaluates the impact of higher temperatures on learning outcomes in Peru. The results suggest that 1 degree above 20°C is equivalent to 7 and 6 percent of a standard deviation of what a student learns in a year for math and reading tests, respectively. These results hold true when the main specification is changed, splitting the sample, collapsing the data at school level, and using other climate specifications. The paper aims to improve understanding of how to deal with the impacts of climate change on learning outcomes in developing countries. The evidence suggests that conditional cash transfer programs can mitigate the negative effects of higher temperatures on students’ learning outcomes in math and reading.
Journal
Journal Volume
Journal Issue
Collections
Related items
Showing items related by metadata.
Publication Joseph E. Stiglitz(World Bank, Washington, DC, 2008-01)Joseph E. Stiglitz, 2001 Nobel Laureate in Economics, helped create the theory of markets with asymmetric information and was one of the founders of modern development economics. He played a leading role in an intellectual revolution that changed the characterization of a market economy. In the new paradigm, the price system only imperfectly solves the information problem of scarcity because of the many other information problems that arise in the economy: the selection over hidden characteristics, the provision of incentives for hidden behaviors and for innovation, and the coordination of choices over institutions.Publication Health Insurance Reform in Four Latin American Countries : Theory and Practice(World Bank, Washington, DC, 2000-11)The author examines public economics rationales for public intervention in health insurance markets, draws on the literature of organizational design to examine alternative intervention strategies, and considers health insurance reforms in four Latin American countries -- Argentina, Brazil, Chile, and Colombia -- in light of the theoretical literature. Equity has been the main reason for large-scale public intervention in the health insurance sector, despite the well-known failures of insurance and health care markets associated with imperfect information. Recent reforms have sought less to make private markets more efficient than to make public provision more efficient, sometimes by altering the focus and function of existing institutions (such as the obras sociales in Argentina) or by encouraging the growth of new ones (such as Chile's ISAPREs). Generally, these four Latin American countries have reformed the ways insurance and care are organized and delivered, have tried to extend formal coverage to previously marginalized groups, and have tried to finance this extension fairly. Colombia instituted an implicit two-tiered voucher scheme financed through a proportional wage tax. Chile's financing mechanism is similar but the distribution of benefits is less progressive, so the net effect is less redistributive. Argentina's remodeled obras system went halfway: the financing base is similar and there is some implicit redistribution from richer to poorer obras, but the quality of insurance increases with income. On the face of it, Brazil's health insurance system is less redistributive than those of the other three countries, as no tax is earmarked for financing health insurance. But taxes paid by higher-income taxpayers are not reduced when they choose private insurance, highlighting the problem of examining the health sector independent of the general tax and transfer system.Publication Weak Links in the Chain II : A Prescription for Health Policy in Poor Countries(World Bank, Washington, DC, 2002-01)This article presents an approach to public policy in health that comes directly from the literature on public economics. It identifies two characteristic market failures in health. The first is the existence of large externalities in the control of many infectious diseases that are mostly addressed by standard public health interventions. The second is the widespread breakdown of insurance markets that leave people exposed to catastrophic financial losses. Other essential considerations in setting priorities in health are the degree to which policies address poverty and inequality and the practicality of implementing policies given limited administrative capacities. Priorities based on these criteria tend to differ substantially from those commonly prescribed by the international community.Publication Social Health Insurance for Developing Nations(Washington, DC: World Bank, 2007)Good health is necessary for well-being but also has another critical impact: it causes poverty, in that large health expenditures can bankrupt families. Many nations are now hoping that formally mandated social health insurance (SHI), involving payroll taxes, will provide a solution. This report examines the principles, design, and practices of SHI for low and middle-income nations and the necessary conditions for its viability and sustainability, with a focus on design and implementation issues. This volume presents five country case studies to provide evidence and greater detail on key issues that arise at different stages of implementation in low-income countries. They have been selected to reflect on a continuum and timeline of operational stages, beginning with the initial design and legislation of SHI, the first phase of implementation, the expansion to cover larger segments of the population, and on up to completion, whereby SHI becomes the predominant form of health care financing in a country. Accordingly, Kenya has been selected for illustration of the design stage, Ghana for initiation, the Philippines for extension of population coverage, Colombia for SHI and reform of health care delivery, and Thailand for universal coverage and reform of health care delivery. This sequencing and implied timeline of case studies allows this report to reflect on two questions. First, where can a country expect to be in relation to designing and implementing SHI in, say, 10 years? Second, as countries gain experience with SHI, what can they expect to offer or achieve in terms of variations in benefit design, who administers SHI, and how providers are contracted and paid?Publication Assessing the Impact of WTO Accession on Belarus(World Bank, Washington, DC, 2016-06)As a small and open economy, Belarus' development perspectives are intrinsically linked to its ability to produce and sell goods and services competitively in the global marketplace. While Belarus is an open economy, its trade links are concentrated both in terms of products and markets. Mineral goods –most importantly refined oil and potassium chloride - are the main export product accounting for more than 1/3 of total exports. Non mineral exports, including most importantly machinery, vehicles and transport equipment are mostly exported to Russia and other CIS markets, which account for 74 percent of non-mineral exports while the share of EU countries in Belarus non-mineral exports account for less than 15 percent. With Russia's WTO accession in 2012 competitive pressures on Belarus’ major market for non-mineral exports have further intensified. As Belarus is accelerating its own negotiations with the WTO, understanding the challenges and opportunities faced by the country's exporters is critical to putting in place an effective adaptation strategy that will enhance competitiveness and ensure Belarus can take full advantage of more open market access. The objective of this note is to analyze the economic impacts of Belarus' potential accession to the WTO. The note utilizes a modern computable general equilibrium model of the economy of Belarus to simulate impacts on the economy as a whole and on individual sectors.
Users also downloaded
Showing related downloaded files
Publication Mexico Poverty and Equity Assessment(Washington, DC: World Bank, 2025-02-20)This Mexico Poverty and Equity Assessment reviews the evidence about poverty and equity in Mexico over the last two decades, compares it to comparable international experience, and identifies a set of critical areas of policy intervention to answer the opening question. The report aims at contributing to an open conversation in Mexico about how to achieve this essential policy objective. This report postulates three main policy areas needed for poverty eradication in Mexico: inclusive growth, efficient social policy, and infrastructure to confront vulnerability. The report includes four sections, the first three of which collect evidence about poverty, social deprivations, and vulnerability and how the evolution of these three correlates to patterns of economic growth, social protection policy and territorial development. The fourth section provides some quantitative benchmarks of what it would take to eradicate extreme poverty in Mexico. Poverty in Mexico is defined not only in monetary terms, but also in a multidimensional manner that includes social deprivations. These are social deprivations that often define formal-vs-informal employment, so policy changes that close these carencias, as they are called in Mexico, will also reduce the informality gap. This report documents the evolution of poverty, social deprivations, and vulnerability to poverty. It explains the main forces that have driven this evolution and advises that many of these forces may not operate the same in the future as they did in the past. It provides the basis to argue that short to medium term extreme poverty eradication requires newer policy actions in terms of inclusive growth, more efficient social policy, and investments in physical and social infrastructure to reduce vulnerability. The report indicates that short to medium term eradication to extreme poverty is a major, but within reach, development challenge for Mexico.Publication Classroom Assessment to Support Foundational Literacy(Washington, DC: World Bank, 2025-03-21)This document focuses primarily on how classroom assessment activities can measure students’ literacy skills as they progress along a learning trajectory towards reading fluently and with comprehension by the end of primary school grades. The document addresses considerations regarding the design and implementation of early grade reading classroom assessment, provides examples of assessment activities from a variety of countries and contexts, and discusses the importance of incorporating classroom assessment practices into teacher training and professional development opportunities for teachers. The structure of the document is as follows. The first section presents definitions and addresses basic questions on classroom assessment. Section 2 covers the intersection between assessment and early grade reading by discussing how learning assessment can measure early grade reading skills following the reading learning trajectory. Section 3 compares some of the most common early grade literacy assessment tools with respect to the early grade reading skills and developmental phases. Section 4 of the document addresses teacher training considerations in developing, scoring, and using early grade reading assessment. Additional issues in assessing reading skills in the classroom and using assessment results to improve teaching and learning are reviewed in section 5. Throughout the document, country cases are presented to demonstrate how assessment activities can be implemented in the classroom in different contexts.Publication Financing Firm Growth(Washington, DC: World Bank, 2025-03-13)Well-functioning capital markets can foster economic growth and allocate resources efficiently. Firms can tap into a broader funding base by issuing debt and equity in capital markets, often at cheaper rates and longer tenors than through other sources of external finance, such as banks. However, capital markets in low- and middle-income countries have lagged those in high-income countries. Accordingly, the firms in those countries have more often relied on bank financing or retained earnings to fund investment and expansion, and they have experienced greater financial constraints than their counterparts in high-income countries. Financing Firm Growth: The Role of Capital Markets in Low- and Middle-Income Countries shows that the gap in capital market financing between low- and middle-income countries and high-income countries has narrowed, with resulting benefits for both the firms accessing those markets and for the countries in which they operate. The analysis reveals greater participation by firms from low- and middle-income countries in capital markets since the 2000s. Most of these firms are new participants in capital markets, and they tend to be smaller, younger, and more productive than those already participating. Firms are deploying capital raised in markets to become more productive—investing in physical assets, hiring more workers, and expanding operations, spurring growth both at the firm level and within their economies. To reach these findings, the analysis used a novel database of the universe of bond and equity issuances from companies between 1990 and 2022. The insights leverage data from nearly 80,000 firms worldwide, focusing on how 20,000 firms across 106 low- and middle-income countries access and use capital market financing. --- “Financing Firm Growth is a groundbreaking exploration that delves into the vital role that capital markets play in driving business expansion in low- and middle-income countries. Backed by data from 80,000 firms across 147 economies, the authors explore the factors underlying capital market growth and its benefits for economies and firms at all levels of development. This book is a must-read for investors, policy makers, and economists shaping the future of global finance.” — Laura Alfaro, Warren Alpert Professor of Business Administration, Harvard Business SchoolPublication Argentina Country Climate and Development Report(World Bank, Washington, DC, 2022-11)The Argentina Country Climate and Development Report (CCDR) explores opportunities and identifies trade-offs for aligning Argentina’s growth and poverty reduction policies with its commitments on, and its ability to withstand, climate change. It assesses how the country can: reduce its vulnerability to climate shocks through targeted public and private investments and adequation of social protection. The report also shows how Argentina can seize the benefits of a global decarbonization path to sustain a more robust economic growth through further development of Argentina’s potential for renewable energy, energy efficiency actions, the lithium value chain, as well as climate-smart agriculture (and land use) options. Given Argentina’s context, this CCDR focuses on win-win policies and investments, which have large co-benefits or can contribute to raising the country’s growth while helping to adapt the economy, also considering how human capital actions can accompany a just transition.Publication World Development Report 2006(Washington, DC, 2005)This year’s Word Development Report (WDR), the twenty-eighth, looks at the role of equity in the development process. It defines equity in terms of two basic principles. The first is equal opportunities: that a person’s chances in life should be determined by his or her talents and efforts, rather than by pre-determined circumstances such as race, gender, social or family background. The second principle is the avoidance of extreme deprivation in outcomes, particularly in health, education and consumption levels. This principle thus includes the objective of poverty reduction. The report’s main message is that, in the long run, the pursuit of equity and the pursuit of economic prosperity are complementary. In addition to detailed chapters exploring these and related issues, the Report contains selected data from the World Development Indicators 2005‹an appendix of economic and social data for over 200 countries. This Report offers practical insights for policymakers, executives, scholars, and all those with an interest in economic development.