Publication:
A Flaw in the Model… That Defines How the World Works

Loading...
Thumbnail Image
Files in English
English PDF (625.5 KB)
489 downloads
English Text (32.83 KB)
273 downloads
Published
2010-12-01
ISSN
Date
2012-03-19
Editor(s)
Abstract
The authors of this paper claim that modeling financial markets based on probability theory is a severe systematic mistake that led to the global financial crisis. They argue that the crisis was not just the result of risk managers using outdated financial data, but that the employed efficiency model -- also referred to as the stochastic model -- is basically flawed. In an exemplary way, the analysis proves that this model is unable to account for interactions between market participants, neglects strategic interdependences, and hence leads to erroneous solutions. The central message is that the existing efficiency model should be replaced by an approach using agent-based scenario analysis.
Link to Data Set
Citation
Bieta, Volker; Milde, Hellmuth; Weber, Nadine. 2010. A Flaw in the Model… That Defines How the World Works. Policy Research working paper ; no. WPS 5498. © World Bank. http://hdl.handle.net/10986/3980 License: CC BY 3.0 IGO.
Associated URLs
Associated content
Report Series
Report Series
Other publications in this report series
  • Publication
    The Macroeconomic Implications of Climate Change Impacts and Adaptation Options
    (Washington, DC: World Bank, 2025-05-29) Abalo, Kodzovi; Boehlert, Brent; Bui, Thanh; Burns, Andrew; Castillo, Diego; Chewpreecha, Unnada; Haider, Alexander; Hallegatte, Stephane; Jooste, Charl; McIsaac, Florent; Ruberl, Heather; Smet, Kim; Strzepek, Ken
    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
    South Africa’s Fragmented Cities: The Unequal Burden of Labor Market Frictions
    (Washington, DC: World Bank, 2026-01-08) Baez, Javier E.; Kshirsagar, Varun
    Using high-resolution administrative, census, and satellite data, this paper shows that South African cities are characterized by spatial mismatches between where people live and where jobs are located, relative to 20 global peers. Areas within 5 kilometers of commercial centers have 9,300 fewer residents per square kilometer than expected, which is 60 percent below the global median. Poor, dense neighborhoods are most affected. In Johannesburg, a 10-percentile increase in distance from the nearest business hub corresponds to a 3.7-percentile drop in asset wealth (a proxy of household wellbeing) and 4.9-percentile drop in employment. In Cape Town, the declines are 4.0 and 3.7 percentiles, respectively. Employment is 87 percent lower in the poorest decile than the richest in Johannesburg and 61 percent lower in Cape Town. These findings suggest that South Africa’s spatial organization of people and economic activity constrains agglomeration and reinforces inequality. This methodology provides a scalable and standardized data-driven framework to analyze spatial accessibility and agglomeration frictions in complex, data-constrained urban systems.
  • Publication
    The Evolution of Local Participatory Democracy in Nepal
    (Washington, DC: World Bank, 2025-11-05) Bhusal, Thaneshwar; Breen, Michael G; Rao, Vijayendra
    Nepal is, according to its constitution, among the world’s most decentralized countries, with a long and complex tradition of local-level public participation. This paper traces the evolution of Nepal’s modern participatory institutions, examining the extent to which they are “induced” by external interventions versus being “organically” rooted in indigenous practices. The paper identifies three broad phases: an initial focus on participation in project implementation; a subsequent phase that expanded citizen engagement; and a third phase of citizen empowerment, culminating in the 2015 federal constitution, which granted unprecedented local autonomy. The analysis yields five key findings. First, over the past 50 years, successive reforms have progressively expanded opportunities for citizens to influence local decision-making. Second, these reforms have integrated traditional participatory mechanisms into formal institutions of local government. Third, although central-level initiatives exist, most participatory platforms continue to operate at the local level. Fourth, the federal constitution has created a new landscape of local democracy, embedding autonomy and accountability. Fifth, although they are still valued in many ethnic and territorial communities, traditional participatory practices are gradually disappearing. The paper concludes by offering policy recommendations to help donor agencies and governments strengthen Nepal’s democratic trajectory. It argues that effective interventions should build on Nepal’s deep participatory traditions while recognizing the constitutional reality of far-reaching local autonomy.
  • Publication
    Institutional Capacity for Policy Implementation: An Analytical Framework
    (Washington, DC: World Bank, 2026-01-07) Kim, Galileu; Kumar, Tanu; Ramalho, Rita; Russell, Stuart
    State capacity is an important prerequisite for policy implementation, yet at the country level it is difficult to measure, assess, and reform. This paper proposes a focus on institutional capacity: the ability of public institutions to implement the specific policy mandates for which they are responsible. Based on a review of existing literature, the paper defines the different dimensions that compose institutional capacity and groups them into two cross-cutting categories: organizational dimensions (personnel, financial resources, information systems, and management practices) and governance dimensions (transparency, independence, and accountability). The paper proposes measures for organizational and governance dimensions using existing data, shows intra-institutional variation of these measures within countries, and discusses how new data could be collected for better measurement of these concepts. Finally, the paper illustrates how the framework can be used to diagnose the sources of common problems related to weak policy implementation.
  • Publication
    Closing the Gender Gap in Entrepreneurship: Overcoming Challenges in Law and Practice for Female Entrepreneurs
    (Washington, DC: World Bank, 2026-01-07) Behr, Daniela M.; Xi, Yue
    Despite significant strides toward gender equality, women around the world continue to encounter systemic obstacles that hinder their entrepreneurial success. This paper systematically reviews the literature on the barriers female entrepreneurs face and the solutions proposed to overcome these challenges. It discusses institutional factors, financial factors, human capital factors, and social and cultural factors. The literature overview is complemented by a series of stylized facts that illustrate how overcoming some of these existing barriers is correlated with improved women’s entrepreneurship and female labor force participation, drawing on the World Bank’s Women, Business and the Law database as well as the World Bank’s Enterprise Surveys. The findings underscore the need for creating an enabling environment where women can thrive as entrepreneurs.
Journal
Journal Volume
Journal Issue

Related items

Showing items related by metadata.

  • Publication
    Strategic Information Revelation and Capital Allocation
    (World Bank Group, Washington, DC, 2014-07) Pedraza Morales, Alvaro
    It is commonly believed that stock prices help firms' managers make more efficient real investment decisions, because they aggregate information about fundamentals that is not otherwise known to managers. This paper identifies a limitation to this view. It shows that if informed traders internalize that firms use prices as a signal, stock price informativeness depends on the quality of managers' prior information. In particular, managers with low quality information would like to learn about their own fundamentals by relying on the information aggregated in the stock price. However, in this case, the profitability of trading falls for informed speculators, who therefore reduce their trading volume, reducing the informativeness of prices. As a result, stock prices are not as useful in guiding capital toward its most productive use, leading to inefficient investment decisions. Using a sample of U.S. publicly traded companies between 1990 and 2010, the paper documents a positive correlation between the quality of managerial information and stock price informativeness. Contrary to the conventional view that less informed managers should rely more on stock prices when making investment decisions, the author finds no differences in the sensitivity of investment to stock prices for different levels of managerial information. The evidence suggests that while firms do learn from prices, the learning channel and its effects on real investment are limited.
  • Publication
    Insurance and Inclusive Growth
    (World Bank, Washington, DC, 2014-06) Lester, Rodney
    While the real sector and governments (along with a few micro economists) have long recognized the core economic role that the insurance function plays, the mainstream economics profession has largely treated it as invisible background. This literature review of the relevant research, most of which has been carried out in the past few decades, demonstrates that the insurance sector contributes at a basic level to inclusive economic growth and the effectiveness of the credit function. It also shows that the latter impact may be particularly fundamental in assisting the poor to avoid poverty traps and to progress economically. However, the research and the theoretical models underpinning it also highlight certain constraints to the efficient utilization of the insurance function. The literature dealing with innovations designed to overcome these constraints is reviewed and successful initiatives and remaining challenges are identified.
  • Publication
    Reserve Requirements in the Brave New Macroprudential World
    (World Bank, Washington, DC, 2014-02) Cordella, Tito; Federico, Pablo; Vegh, Carlos; Vuletin, Guillermo
    Using a new, large data set on quarterly reserve requirements for the period 1970-2011, this paper provides new evidence on the use of reserve requirements as a countercyclical macroprudential tool in developing countries. The appeal of reserve requirements lies in the pro-cyclical behavior of the exchange rate over the business cycle in developing countries. This enormously complicates the use of interest rates as a countercyclical instrument (because of its effect on the exchange rate) and calls for a second instrument. The paper suggests that conflicts may arise between the microprudential and macroprudential policy stances.
  • Publication
    Corporate Governance and Development
    (International Finance Corporation, Washington, DC, 2012-04-23) Claessens, Stijn; Yurtoglu, Burcin
    What do we know about the links between economic development and corporate governance in emerging markets? Stijn Claessens and Burcin Yurtoglu have sifted through scores of academic studies on various countries, sectors, and business organizations - from state-owned enterprises to publicly listed companies - to determine how corporate governance can influence economic development and well being, and what is needed to promote good practices. The Focus 10 draws on new evidence that has become available since Focus 1: Corporate Governance and Development was published in 2003. While the paper reviews research literature, it is written to be accessible to the nonacademic audience: board members, investors, government regulators, development professionals, and other CG practitioners. Research findings sited in the Focus include: 1) improved corporate governance practices increase firm share prices; 2) operational performance is higher in better corporate governance countries; 3) well governed companies have less volatile stock prices in times of crisis; 4) companies with boards composed of a higher fraction of outsider or independent directors usually have a higher market valuation; 5) improvements in corporate governance quality lead to higher GDP growth, productivity growth, and the increased ratio of investment to GDP; 6) when a country's overall corporate governance and property rights systems are weak, voluntary and market corporate governance mechanisms have limited effectiveness; 7) large, more concentrated ownership can be beneficial, unless there is a disparity of control and cash flow rights; 8) the quality of shareholder protection positively correlates with the development of countries' capital markets; and 9) better corporate governance leads to a better developed financial system. The paper concludes by identifying several main policy and research issues that require further study. For example, more research is needed on family-owned, state-owned or controlled firms that predominate in many sectors and economies. For more publications on IFC Sustainability please visit www.ifc.org/sustainabilitypublications.
  • Publication
    The Unexpected Global Financial Crisis : Researching Its Root Cause
    (2012-01-01) Treichel, Volker; Lin, Justin Yifu
    The world is currently still struggling with the aftermath of the worst economic crisis since the Great Depression. Following a description of the eruption, evolution and consequences of the global crisis, this paper reviews alternative hypotheses for the causes of the global financial crisis as well as their empirical evidence. The paper refutes the frequently voiced view that the global crisis was caused by global imbalances that reflected economic policies of East Asian countries. Instead, it argues that global imbalances were the result of excess demand in the United States, resulting from both the public debt in the United States arising from the Afghanistan and Iraqi wars and tax cuts and the overconsumption by households supported by the wealth effect from the housing bubble in the United States. The housing bubble itself was the outcome of the Federal Reserve's low interest rate policy in the aftermath of the burst of the "dot-com" bubble in 2001, the lack of appropriate financial regulation, and housing policies aimed at expanding the mortgage market to low-income borrowers. It was possible to maintain the large trade deficits of the United States for such a long period of time because of the dollar's reserve currency status. When the housing bubble in the United States burst, the global crisis ensued. The paper also analyzes why China's trade surplus increased significantly in general and with the United States in particular in recent years, and argues that this increase was caused by both the relocation of the labor-intensive tradable sector of East Asian economies to China and high corporate saving rates in China as a result of its dual-track approach to reform.

Users also downloaded

Showing related downloaded files

  • Publication
    Digital Africa
    (Washington, DC: World Bank, 2023-03-13) Begazo, Tania; Dutz, Mark Andrew; Blimpo, Moussa
    All African countries need better and more jobs for their growing populations. "Digital Africa: Technological Transformation for Jobs" shows that broader use of productivity-enhancing, digital technologies by enterprises and households is imperative to generate such jobs, including for lower-skilled people. At the same time, it can support not only countries’ short-term objective of postpandemic economic recovery but also their vision of economic transformation with more inclusive growth. These outcomes are not automatic, however. Mobile internet availability has increased throughout the continent in recent years, but Africa’s uptake gap is the highest in the world. Areas with at least 3G mobile internet service now cover 84 percent of Africa’s population, but only 22 percent uses such services. And the average African business lags in the use of smartphones and computers as well as more sophisticated digital technologies that catalyze further productivity gains. Two issues explain the usage gap: affordability of these new technologies and willingness to use them. For the 40 percent of Africans below the extreme poverty line, mobile data plans alone would cost one-third of their incomes—in addition to the price of access devices, apps, and electricity. Data plans for small- and medium-size businesses are also more expensive than in other regions. Moreover, shortcomings in the quality of internet services—and in the supply of attractive, skills-appropriate apps that promote entrepreneurship and raise earnings—dampen people’s willingness to use them. For those countries already using these technologies, the development payoffs are significant. New empirical studies for this report add to the rapidly growing evidence that mobile internet availability directly raises enterprise productivity, increases jobs, and reduces poverty throughout Africa. To realize these and other benefits more widely, Africa’s countries must implement complementary and mutually reinforcing policies to strengthen both consumers’ ability to pay and willingness to use digital technologies. These interventions must prioritize productive use to generate large numbers of inclusive jobs in a region poised to benefit from a massive, youthful workforce—one projected to become the world’s largest by the end of this century.
  • Publication
    Taxes, Spending, and Equity: International Patterns and Lessons for Developing Countries
    (Washington, DC: World Bank, 2025-11-17) Wai-Poi, Matthew; Sosa, Mariano; Bachas, Pierre
    Taxes and public spending underpin the basic administration of government and finance the human capital and infrastructure investments needed for economic growth. They can also have a significant and immediate impact on poverty and inequality. The question of how public finance can support longer-term growth objectives while promoting equity has become even more important in recent years, given the high fiscal deficits and debt levels most countries emerged with in the aftermath of the COVID-19 pandemic. These included the increasing cost of debt and the need to restart environmentally sustainable growth while helping households address the learning losses and other social scars caused by the pandemic. This paper examines the global evidence on which households pay which taxes and who benefits from what spending, and critically, the net effect on different households across the income distribution. The aim is to identify the patterns and lessons that emerge for designing progressive fiscal policies. A global dataset of 96 countries is assembled, spanning all regions of the world and all national income levels, grounded in the Commitment to Equity (CEQ) approach to fiscal incidence.
  • Publication
    Kyrgyz Republic Country Climate and Development Report
    (Washington, DC: World Bank, 2025-11-03) World Bank Group
    This Country Climate and Development Report (CCDR) on the Kyrgyz Republic aims to support the country’s development goals amid a changing climate. The CCDR considers two policy scenarios up to 2050: the business-as-usual (BAU) and high-growth scenarios. As it quantifies the likely impacts of climate change on the Kyrgyz economy between now and 2050, the report highlights key government actions to best prepare for and adapt to climate impacts (referred to as “with adaptation” measures), with a particular focus on the time horizon up to 2030. The CCDR also outlines a path to net zero emissions by 2050 (referred to as “with mitigation” measures, “decarbonization,” or, simply, “net zero 2050”), highlighting associated development co-benefits.
  • Publication
    Direct and Indirect Impacts of Transport Mobility on Access to Jobs: Evidence from South Africa
    (Washington, DC: World Bank, 2025-11-12) Iimi, Atsushi
    Access to jobs is essential for economic growth. In Africa, unemployment rates are notably high. This paper reexamines the relationship between transport mobility and labor market outcomes, with a particular focus on the direct and indirect effects of transport connectivity. As predicted by theory, wages are influenced by the level of commuting deterrence. Generally, higher earnings are associated with longer commute times and/or higher commuting costs. Local accessibility is also important, especially for individuals with time constraints. Both direct and indirect impacts are found to be significant in South Africa, where job accessibility has been challenging since the end of apartheid. For the direct impact, the wage elasticity associated with commuting costs is significant. Returns on commute are particularly high for women. Local accessibility to socioeconomic facilities, such as shops and health services, is also found to have a significant impact, consistent with the concept of mobility of care. To enhance employment, therefore, it is crucial to connect people not only to job locations but also to various socioeconomic points of interest, such as markets and hospitals, in an integrated manner. This integration will enable individuals to spend more time working and commuting longer distances.
  • Publication
    Continental Drying: A Threat to Our Common Future
    (Washington, DC: World Bank, 2025-11-04) Zhang, Fan; Borja-Vega, Christian; Chandanpurkar, Hrishikesh Arvind; Famiglietti, James; Hogeboom, Rick; Namara, Regassa; Rasul, Zarif; Luengas-Sierra, Pavel; Rao, Deyu
    Grounded in new evidence from satellite data, “Continental Drying: A Threat to Our Common Future” presents the first global assessment of freshwater reserves over the past two decades. The findings expose an alarming trend of “continental drying,” a persistent long-term decline in freshwater availability across vast landmasses. Not only are droughts and deluges becoming more unpredictable, but the total amount of freshwater available for use has also significantly declined. Continental drying, driven by global warming, worsening droughts, and unsustainable water and land use, is a silent but accelerating crisis—largely unknown to the public—that reshapes the global water narrative. Continental drying raises profound risks. This report reveals new empirical evidence showing how freshwater depletion leads to major job losses, reduced incomes, wildfires, and biodiversity threats. In the long term, the combined effects of drying and warming could push societies toward a tipping point where damage accelerates rapidly and adaptation becomes increasingly difficult. Against the backdrop of continental drying, global water consumption rose by 25 percent between 2000 and 2019, with about a third of this increase occurring in regions already experiencing drying. Compounding the pressure, a substantial share of water use in drying regions remains inefficient. Continental Drying identifies hot spots where rising demand and declining supply converge and explores where and how water savings can be realized. This report recommends a three-pronged approach to address the crisis: managing demand, augmenting water supply, and improving water allocation. Five cross-cutting levers—strengthening institutions, reforming water tariffs and repurposing subsidies, adopting water accounting, leveraging data and technological innovations, and valuing water in trade—are essential for effective implementation and to attract private investment to finance the approach. Beyond water, addressing trade barriers, investing in education and skills development, and improving access to markets and financial services are critical for strengthening job and livelihood resilience amid a continental drying crisis.