The Gini coefficient remains a popular gauge of inequality throughout the social and natural sciences because it is visually striking and geometrically intuitive. It measures the “gap” between a hypothetically equal distribution of income or wealth and the actual distribution. But not all inequality curves yielding the same Gini coefficient are unequal in the same way. The Lorenz asymmetry coefficient, a second-order measure of asymmetry, provides further information about the distribution of income or wealth. To add even more interpretive power, this paper proposes a new angular measure derived from the Lorenz asymmetry coefficient. Adjusted azimuthal asymmetry is the angular distance of the Lorenz asymmetry coefficient from the axis of symmetry, divided by the maximum angular distance that can be attained for any given Gini coefficient.
Thursday, May 21, 2015
Saturday, April 25, 2015
Jurisdynamics is pleased to have received, courtesy of Oxford University Press, Climate Change Impacts on Ocean and Coastal Law: U.S. and International Perspectives (Randall S. Abate ed., 2015), available via http://bit.ly/ClimateChangeOceanLaw. The publisher's note succinctly describe the book's mission:
Ocean and coastal law has grown rapidly in the past three decades as a specialty area within natural resources law and environmental law. The protection of oceans has received increased attention in the past decade because of sea-level rise, ocean acidification, the global overfishing crisis, widespread depletion of marine biodiversity such as marine mammals and coral reefs, and marine pollution. Paralleling the growth of ocean and coastal law, climate change regulation has emerged as a focus of international environmental diplomacy, and has gained increased attention in the wake of disturbing and abrupt climate change related impacts throughout the world that have profound implications for ocean and coastal regulation and marine resources.
This monumental volume is the authoritative source on the subject. As anthropogenic climate change puts a deeper stamp on the planet, this book's significance is certain to rise.
Sunday, March 01, 2015
Economic analysis of technological innovation, diffusion, and decline often proceeds according to sigmoid (S-shaped) models, either directly or as a component in more elaborate mathematical representations of the creative process. Three distinct aspects of American innovation policy — Aereo’s failed attempt to retransmit television broadcasts, agricultural biotechnology, and network neutrality — invite analysis according to one variant or another of the logistic function. Innovation and legal policies designed to foster it follow the leaps, metes, and bounds of sigmoid functions.
Part I introduces the logistic function as the simplest analytical expression of a sigmoid function. Its parameters provide very clear interpretations grounded in physical principles. Part II evaluates the Aereo controversy and agricultural biotechnology as instances of logistic substitution between competing products. The deployment of plant-incorporated pesticides and herbicide-resistant crops arguably follows the Hubbert curve, a related function that describes peak production of depletable resources and their eventual exhaustion. Part III proposes multiple ways of understanding network neutrality as a problem of multilayered innovation. The presence of two different types of nonlinear growth, in network operating costs and in expressive diversity online, suggests that the law should prescribe independent rather than bundled solutions to these conceptually distinct subjects.
Thursday, January 08, 2015
The 15th annual workshop on Conducting Empirical Legal Scholarship, co-taught by Lee Epstein and Andrew D. Martin, will run from June 15-17, 2015, at Washington University in St. Louis. The workshop is for law school faculty, lawyers, political science faculty, and graduate students interested in learning about empirical research and how to evaluate empirical work. It provides the formal training necessary to design, conduct, and assess empirical studies, and to use statistical software (Stata) to analyze and manage data.
Participants need no background or knowledge of statistics to enroll in the workshop. Registration is here. For more information, please contact Lee Epstein.
Wednesday, November 26, 2014
Price-level, or “price-cap,” regulation offers an alluring alternative to the traditional technique of monitoring a regulated firm’s profits. Part II of this article contrasts price-level regulation with conventional cost-of-service ratemaking and with Ramsey pricing. Price-level regulation stands as a market-based, incentive-driven “third way” between traditional regulation and complete deregulation. Part III provides formal specifications of price-level regulation. Although some jurisdictions have set price caps according to operating cost and rate-of-return calculations that clearly parallel those steps in conventional ratemaking, this article will focus on price-level methodologies that combine an economy-wide measure of inflation with an x-factor reflecting total factor productivity within a regulated industry.
Part IV addresses the simpler component of price-level regulation, the choice of an inflation index. Part V devotes detailed attention to the treatment of the x-factor by two federal ratemaking agencies, the Federal Energy Regulatory Commission (FERC) and the Federal Communications Commission (FCC). Closer examination of price cap methodologies adopted by FERC and the FCC suggests that price-level regulation based on inflation and an industry-specific X factor may be further streamlined. Part VI describes how price-level regulation might be accomplished through the application of a single, industry-specific index of input costs.
Wednesday, August 13, 2014
Call for papers
Ebola and the Law
Biolaw section of the Association of American Law Schools (AALS)
Monday, January 5, 2015, 10:30 a.m. to 12:15 p.m.
The 2014 west African outbreak of the Ebola virus is the most severe epidemic attributed to this pathogen since 1976, when international health officials began keeping records on Ebola. As of August 2014, the total number of suspected cases has approached 2,000, and the number of suspected deaths has exceeded 1,000. The World Health Organization has designated the health crisis as one of international concern. The law has a strong stake in containing this outbreak and preventing future episodes of this kind.
The Biolaw section of the AALS invites papers addressing issues of law and policy arising from the Ebola outbreak. Such issues may include (but by no means are limited to) the following:
- Why was the international legal and public health community so slow to recognize the 2014 Ebola outbreak? Human beings are supremely attuned to threats posed by other humans (such as war or terrorism), but far less prepared for threats deemed "natural" or "environmental." How should law accommodate and/or offset this biological predisposition?
- There is no vaccine or cure for Ebola. Medicines for treating Ebola, carrying some hope of reducing the mortality rate, are in extremely short supply. What are the bioethical implications raised by the decision to devote the extremely limited supplies of Ebola medication — no more than a handful of doses as of August 2014 — to medical workers of non-African origin? How should the U.S. Food and Drug Administration and its foreign counterparts handle petitions to expedite the experimental use of Ebola medication?
- The failure to contain Ebola to a few, geographically concentrated cases has enabled the virus to infect four countries (Guinea, Sierra Leone, Liberia, and Nigeria) as of August 2014. Relatively severe public heath measures, ranging from the quarantine to the cordon sanitaire, are contemplated and may be implemented in varying degrees in one or more affected countries. What are the legal and ethical implications of resort to law enforcement or even military solutions during public health emergencies?
- Outbreaks of Ebola and other highly communicable diseases are all but inevitable in an age of globalization, anthropogenic climate change, and biodiversity loss. Even apart from the bushmeat trade, which is suspected of enabling epizootics to make the jump to humans, increased human traffic into previously untouched areas has introduced viruses and other pathogens to human populations around the world. What if any solutions can the law provide, through its focus on environmental protection, immigration, trade, and human rights?
Please submit your proposals to Biolaw section chairman Jim Chen at email@example.com by September 26, 2014. The section will explore channels for publishing papers presented in this program. The program will take place at the 2015 midyear meeting of the AALS in Washington, D.C., at 10:30 a.m. to 12:15 p.m. on Monday, January 5, 2015.
Eligibility: Full-time faculty members of AALS member law schools are eligible to submit papers. Foreign, visiting (without a full-time position at an AALS member law school) and adjunct faculty members; graduate students; fellows and non-law school faculty are not eligible to submit. Faculty at fee-paid non-member schools are ineligible.
Wednesday, April 23, 2014
Minority Television Project, Inc. v. FCC, No. 13-1124, Brief for Amici Curiae Law Professors in Support of Petitioner
Minority Television Project, Inc. v. FCC, No. 13-1124, Brief for Amici Curiae Law Professors in Support of Petitioner, available at http://bit.ly/MinorityTelevisionAmicus:
This brief amicus curiae in support of petitioner Minority Television Project in Minority Television Project, Inc. v. FCC, 736 F.3d 1192 (9th Cir. 2013), petition filed, No. 13-1124 (March 17, 2014), urges the Supreme Court of the United States to overrule Red Lion Broadcasting Co. v. FCC, 395 U.S. 367 (1969). The brief presents three reasons why the Court should overrule Red Lion. First, overwhelming technological change compels reexamination of Red Lion. The proliferation of electronic media for distributing multichannel audio and video programming has undermined Red Lion’s scarcity rationale. Second, Red Lion has been so thoroughly discredited in all branches of government that further adherence to that precedent would undermine rather than promote respect for the Court’s decisionmaking process and for the rule of law. Finally, this case demonstrates how the continued isolation of broadcast media from First Amendment norms that govern all other media and conduits inflicts serious harm to the constitutional interest in free speech.
The academic signatories of this brief were:
- Ashutosh A. Bhagwat (UC Davis)
- Dale Carpenter (Minnesota)
- James Ming Chen (Michigan State)
- Eric M. Freedman (Hofstra)
- Patrick Garry (South Dakota)
- Mehmet K. Konar-Steenberg (William Mitchell)
- Lyrissa Barnett Lidsky (Florida)
- Kevin Francis O'Neil (Cleveland State)
- Michael Stokes Paulsen (St. Thomas, Minnesota)
- Daniel D. Polsby (George Mason)
- Lucas A. Powe, Jr. (Texas)
- Matthew L. Spitzer (Northwestern)
- Eugene Volokh (UCLA)
Wednesday, March 26, 2014
James Ming Chen, An Agricultural Law Jeremiad: The Harvest Is Past, the Summer Is Ended, and Seed Is Not Saved, 2014 Wisconsin Law Review (forthcoming), available at http://ssrn.com/abstract=2387998 or http://bit.ly/SeedIsNotSaved, and to be presented on March 26, 2014, at the University of Michigan Law School's Intellectual Property Workshop:
The saving of seed exerts a powerful rhetorical grip on American agricultural law and policy. Simply put, farmers want to save seed. Many farmers, and many of their advocates, believe that saving seed is essential to farming. But it is not. Farmers today often buy seed, just as they buy other agricultural inputs. That way lies the path of economic and technological evolution in agriculture. Seed-saving advocates protest that compelling farmers to buy seed every season effectively subjects them to a form of serfdom. So be it. Intellectual property law concerns the progress of science and the useful arts. Collateral economic and social damage, in the form of affronts to the agrarian ego, is of no valid legal concern. The harvest is past, the summer is ended, and seed is not saved.
Thursday, March 20, 2014
The basic tenets of prospect theory, a bedrock principle of behavioral economics, can be illustrated by what Daniel Kahneman has called prospect theory’s "flag": an asymmetrical sigmoid curve whose inflection point occurs at the origin (thus reflecting human beings' adaptation level relative to their starting economic position), whose slope to the left of the origin is discernibly steeper than its slope to the right (thus reflecting loss aversion), and whose upper and lower asymptotes reflect diminishing sensitivity to losses as well as gains.
This paper describes a surprisingly simple and supple method for parametrically modeling prospect theory with closed-form expressions and elementary functions. It accomplishes this task by transforming the cumulative distribution function of the log-logistic distribution. In plainer language, this paper “draws” the flag of prospect theory with the simplest available mathematical functions and the minimum amount of algebraic manipulation needed to generate that flag. The resulting formula can expressed with exactly two parameters. That formula can be readily modified to fit empirical data garnered in support of nearly any hypothesis informed by prospect theory.
Friday, March 07, 2014
Oxford University Press has kindly added a new item to the Jurisdynamics Network's bookshelf: Louis Fisher, The Law of the Executive Branch Presidential Power, part of the new series, Oxford Commentaries on American Law. A description of Presidential Power, drawn from Oxford's blurb, follows.
From the framing of the Constitution to the present day, politicians, scholars, and the public have disputed the precise scope of presidential authority in the United States. Epic struggles have tested the bases for presidential appointment and removal, the President's power over the military and as Commander-in-Chief of American forces, and the President's ability to conceal the identity of those who have advised him in evaluating and making policy. The law of the executive branch covers not just the White House, but all executive staff and all of the agencies of the United States.
This book reviews all sources of the law of the executive branch, from the text of the Constitution and the intent of its framers through more than two centuries of practice and tradition. Louis Fisher reviews case law, presidential initiatives, congressional statutes, and public and international sources to inform his own interpretation of legitimate versus illegitimate exercises of power, The book addresses the full range of presidential controversies, including unilateral presidential wars, the state secrets privilege, claims of "inherent" power beyond the reach of the other branches of government, and executive privilege.
Monday, March 03, 2014
Oxford University Press has very generously added Daniel N. Shaviro, Fixing U.S. International Taxation (2014) to the Jurisdynamics Network bookshelf. A brief description, drawn from Oxford's blurb for this book, follows.
Through Fixing U.S. International Taxation, Daniel Shaviro has undertaking a thorough reconceptualization of the United States' approach to international tax law and policy. The United States has compounded the longstanding and sterile debate over international taxation, which is stuck in an obsessive rut over putative "double taxation." The current debate locks tax policy into an all-or-nothing choice between global or residence-based taxation of American companies coupled with foreign tax credits, on one hand, and outright exemption of foreign source income, on the other hand. Rejecting both solutions and, indeed, the entire framework, Shaviro proposes a complete reformulation in the hope of reshaping the treatment of foreign taxes and the determination of tax rates on foreign source income. As a matter of methodology, this volume unites international taxation with the literature on public economics and international trade.
Wednesday, February 05, 2014
Scarcely any legal question arises in the United States that is not resolved, sooner or later, through arbitration. If Alexis de Tocqueville could survey contemporary American legal culture, he would rub his eyes with amazement at the privatization of adjudication across a wide swath of issues previously committed to judicial resolution. From trade disputes posing serious questions of economic diplomacy to consumer contracts adhering to cell phones and credit cards, mandatory arbitration has displaced conventional adjudication. In the country that de Tocqueville characterized as driven by its dedication to constitutional lawmaking through litigation, arbitration has become a dominant form of dispute resolution with little if any direct doctrinal influence by federal constitutional law. This is the overriding theme of Peter B. Rutledge’s new book, Arbitration and the Constitution.
I also discussed at the American Enterprise Institute and Federalist Society's March 26, 2013, forum on Arbitration and the Constitution. The video archive of my contribution to that forum appears below:
Sunday, February 02, 2014
In principle, neither the global environment nor personal health should come down to gambling. In practice, however, both the law of global biodiversity protection and the constitutional debate on the Patient Protection and Affordable Care Act (PPACA) rest on astoundingly risk-seeking assumptions. Charged with conserving the global biospheric commons, the international community seems eager to place deep, out-of-the-money bets on bioprospecting of rare and endangered species for pharmaceutical gain. The truly desperate state of biodiversity and climate change law has apparently prompted some very rich countries (especially the United States) to behave as if these sources of truly irreparable environmental harm defy meaningful precautions.
Within America’s own borders, the constitutional law of public health strikes a comparably risk-seeking pose. Although National Federation of Independent Business v. Sebelius upheld the PPACA as an exercise of the federal government's taxing authority, it reasoned that a directive aimed at uninsured individuals to buy health insurance lay beyond the power of Congress to regulate interstate commerce. If Congress may not compel people to buy health insurance, precisely because those individuals believe that they are better off bearing the relatively modest risk of catastrophic illness or injury, Congress may not have constitutional power to compel wage-earners to accept annuities or annuity-like income streams.
International environmental law and American health law act perversely precisely because they force life-and-death choices at the very points where emotion overrides reason. These otherwise baffling phenomena manifest different facets of prospect theory, the leading behavioral account of risk aversion and risk-seeking. These two bodies of law provide enough material to cover the entire pinwheel-shaped “fourfold pattern” that defines prospect theory. So spins the law’s pinwheel of fortune.
Saturday, January 25, 2014
James Ming Chen, Coherence Versus Elicitability in Measures of Market Risk, available at http://ssrn.com/abstract=2385137 and http://bit.ly/CoherenceElicitability:
The Basel II and III accords prescribe distinct measures of market risk in the trading book of regulated financial institutions. Basel II has embraced value-at-risk (VaR) analysis, while Basel III has suggested that VaR be replaced by a different measure of risk, expected shortfall. These measures of risk suffer from mutually irreconcilable flaws. VaR fails to satisfy the conditions required of coherent measures of risk. Conversely, expected shortfall fails the mathematical requirements for elicitability. Mathematical limitations therefore force a choice between theoretically sound aggregation of risks and reliable backtesting of risk forecasts against historical observations.
This research note is a condensed version of Measuring Market Risk Under Basel II, 2.5, and III: VaR, Stressed VaR, and Expected Shortfall, a full working paper posted at http://ssrn.com/abstract=2252463.
The Jurisdynamics bookbag: Flinders, Defending Politics, and Fatovic & Kleinerman, Extra-Legal Power and Legitimacy
Jurisdynamics is pleased to note two books from its mailbox, one from a little while back; the other, brand new.
Matthew Flinders, Defending Politics: Why Democracy Matters in the Twenty-First Century posts a classic apologia for politics. From the Oxford University Press blurb:
Citizens around the world have become distrustful of politicians, skeptical about democratic institutions, and disillusioned about the capacity of democratic politics to resolve pressing social concerns. Many feel as if something has gone seriously wrong with democracy. Those sentiments are especially high in the U.S. as the 2012 election draws closer. In 2008, President Barack Obama ran — and won — on a promise of hope and change for a better country. Four years later, that dream for hope and change seems to be waning by the minute. Instead, disillusionment grows with the Obama adminstration's achievements, or depending where you fall on the spectrum, its lack thereof.
Defending Politics meets this contemporary pessimism about the political process head on. In doing so, it aims to cultivate a shift from the negativity that appears to dominate public life towards a more buoyant and engaged "politics of optimism." Matthew Flinders makes an unfashionable but incredibly important argument of utmost simplicity: democratic politics delivers far more than most members of the public appear to acknowledge and understand. If more and more people are disappointed with what modern democratic politics delivers, is it possible that the fault lies with those who demand too much, fail to acknowledge the essence of democratic engagement, and ignore the complexities of governing in the twentieth century? Is it possible that the public in many advanced liberal democracies have become "democratically decadent," that they take what democratic politics delivers for granted? Would politics appear in a better light if we all spent less time emphasizing our individual rights and more time reflecting on our responsibilities to society and future generations?
Disillusionment with politics is a perennial, even perpetual theme. When even Glenn Beck laments its excesses, books such as Defending Politics will find a welcome home on our shelves.
Of more recent vintage is a volume edited by Clement Fatovic and Benjamin A. Kleinerman, Extra-Legal Power and Legitimacy: Perspectives on Prerogative. Again from Oxford University Press's blurb:
Constitutional systems aim to regulate government behavior through stable and predictable laws, but when their citizens' freedom, security, and stability are threatened by exigencies, often the government must take extraordinary action regardless of whether it has the legal authority to do so. Extra-Legal Power and Legitimacy: Perspectives on Prerogative … examine[s] the costs and benefits associated with different ways that governments have wielded extra-legal powers in times of emergency. They survey distinct models of emergency governments and draw diverse and conflicting approaches by joining influential thinkers into conversation with one another. Chapters by eminent scholars illustrate the earliest frameworks of prerogative, analyze American perspectives on executive discretion and extraordinary power, and explore the implications and importance of deliberating over the limitations and proportionality of prerogative power in contemporary liberal democracy.
Though more narrow in its focus than Defending Politics, this collection of essays highlights a core concern in the post-September 11 era. From covert intelligence to overt power, contemporary politics transcends traditional legal limits on the use of force. Jurisdynamics commends both of these volumes to its readers' attention.
Friday, December 27, 2013
The Jurisdynamics Network has received two radically different but equally intriguing new books, both from Oxford University Press.
W.A. Bogart, Regulating Obesity? Government, Society, and Questions of Health (2014) is a worthy successor to the same author's 2010 monograph, Permit But Discourage: Regulating Excessive Consumption. Bogart, a professor of law at the University of Windsor, argues that laws aimed at promoting healthier lifestyles by encouraging weight loss have mostly failed. Instead of preventing obesity, these laws have merely fueled prejudice against fat people. Oxford's summary captures the essence of Professor Bogart's call for "shifting norms away from stigmatization of the obese and towards more nutritious and healthy lifestyle habits in addition to the acceptance of bodies in all shapes and sizes":
Part of this challenge lies in the complex effects of law and its relationship with norms, including the unintended consequences of regulation. Regulating Obesity? begins by arguing for the protection of the overweight and obese from discrimination through human rights laws. It then examines three other areas of interventions — marketing, fiscal policy, and physical activity — and how these interventions operate within the context of "health equity." Professor Bogart evaluates the effectiveness of legal regulation in addressing obesity and concludes that a healthier population is more important than a thinner population. Regulating Obesity? is the first book to engage in the comprehensive evaluation of this role for law and the implications of society's fascination with regulating consumption.
Oxford's second offering is Robert H. Wagstaff, Terror Detentions and the Rule of Law: US and UK Perspectives (2013). Again, from Oxford's summary:
After the 9/11 terrorist attacks, the United States and the United Kingdom detained suspected terrorists in a manner incompatible with the due process, fair trial, and equality requirements of the Rule of Law. The legality of the detentions was challenged and found wanting by the highest courts in the US and UK. The US courts approached these questions as matters within the law of war, whereas the UK courts examined them within a human rights criminal law context.
In Terror Detentions and the Rule of Law: US and UK Perspectives, Dr. Robert H. Wagstaff documents President George W. Bush's and Prime Minister Tony Blair's responses to 9/11, alleging that they failed to protect the human rights of individuals suspected of terrorist activity. The analytical focus is on the four US Supreme Court decisions involving detentions in Guantanamo Bay and four House of Lords decisions involving detentions that began in the Belmarsh Prison. These decisions are analyzed within the contexts of history, criminal law, constitutional law, human rights and international law, and various jurisprudential perspectives. In this book Dr. Wagstaff argues that time-tested criminal law is the normatively correct and most effective means for dealing with suspected terrorists. He also suggests that preventive, indefinite detention of terrorist suspects upon suspicion of wrongdoing contravenes the domestic and international Rule of Law, treaties and customary international law. As such, new legal paradigms for addressing terrorism are shown to be normatively invalid, illegal, unconstitutional, counter-productive, and in conflict with the Rule of Law.
Tuesday, September 17, 2013
Wednesday, July 17, 2013
[G]iven current tuition levels, the median and even 25th percentile annual earnings premiums justify enrollment. For most law school graduates, the net present value of a law degree typically exceeds its cost by hundreds of thousands of dollars.
We improve upon previous studies by tracking lifetime earnings of a large sample of law degree holders. Previous studies focused on starting salaries, generic professional degree holders, or the subset of law degree holders who practice law. We also include unemployment and disability risk rather than assume continuous full time employment.
After controlling for observable ability sorting, we find that a law degree is associated with a 60 percent median increase in monthly earnings and 50 percent increase in median hourly wages. The mean annual earnings premium of a law degree is approximately $53,300 in 2012 dollars. The law degree earnings premium is cyclical and recent years are within historic norms.I plan on blogging about various aspects of this paper in coming weeks and months. At the outset, I just want to note: I don't share Simkovic's outlook on many matters, including, say, his proposal for risk-based student loans (which is a bit too close to Rick Scott's education agenda for my comfort). I am much closer to the Bady/Konczal view of the role of education (and the state in funding it). I think Simkovic & McIntyre may be too sanguine about the politically driven changes in demand for legal services. (Regardless of how well law schools teach and train, there will be less demand for lawyers in an era of corporate impunity.) Nevertheless, I am deeply impressed with the paper (and the authors' PowerPoint presentation anticipating many critics' concerns). This is important work that should be carefully considered by anyone proposing deep changes in legal education.
Saturday, April 20, 2013
Quantitative finance traces its roots to modern portfolio theory. Despite the deficiencies of modern portfolio theory, mean-variance optimization nevertheless continues to form the basis for contemporary finance. The term "postmodern portfolio theory" expresses many of the theoretical advances in financial learning since the original articulation of modern portfolio theory. Any complete overview of financial risk management must address all aspects of portfolio theory, from the beautiful symmetries of modern portfolio theory to the disturbing behavioral insights and the vastly expanded mathematical arsenal of the postmodern critique. This article surveys portfolio theory, from its modern origins through more sophisticated, “postmodern” incarnations, according to the first four moments of any statistical distribution: mean, variance, skewness, and excess kurtosis. Mastery of these quantitative tools and associated behavioral insights holds the key to the efficient frontier of risk management.
Wednesday, April 17, 2013
Each of the most recent accords of the Basel Committee on Banking Regulation, known as Basel II, 2.5, and II, has embraced a different primary measure of market risk in global banking regulation: traditional value-at-risk (VaR), stressed VaR, and expected shortfall. After introducing the mathematics of VaR and expected shortfall, this note will evaluate how well the reforms embraced by Basel 2.5 and III — stressed VaR and expected shortfall — have addressed longstanding regulatory concerns with traditional VaR.
Part I describes the calculation of VaR in its conventional form. For illustrative purposes, Part I will describe parametric VaR on a Gaussian distribution. Part II summarizes known weaknesses in VaR, from inherent model and estimation risk to VaR’s failure to perform under extreme economic stress and VaR’s failure to satisfy the theoretical constraints on “coherent” measurements of risk. Part III describes how to calculate expected shortfall as an extension of conditional VaR. It further describes how expected shortfall, but not VaR, provides a coherent measure of risk. Part III then reverses field. It explains how VaR, but not expected shortfall (or, for that matter, nearly every other general spectral measure of risk), satisfies the mathematical requirement of “elicitability.” Mathematical limitations on measures of risk therefore force regulators and bankers to choose between coherence and elicitability, between theoretically sound consolidation of diverse risks (on one hand) and reliable backtesting of risk forecasts against historical observations.
Monday, January 07, 2013
The Ganges River begins at the foot of the Gangotri Glacier in the Himalayas and culminates at the Sundarbans Delta, a massive sprawl of swamps, lakes, and scores of islands. (Find an earlier post on the Ganges here.) It’s the largest river delta in the world—home to endangered Bengal tigers, miles of mangroves, and nearly 12 million people (4.5 million on the Indian side and 7.5 million on the Bangladeshi side).
A student of the Mississippi River Delta, I had long wanted to visit the Sundarban Islands. So after giving a series of lectures in Kolkata, I accepted an invitation to visit some of the islands on a medical boat, operated by the Southern Health Improvement Samity, an organization in West Bengal that delivers health-care services to island villagers.
The experience was one of the high points of my semester sabbatical, which has now drawn to a close. The people were lovely. I chatted with a group of young girls about their new school building, which doubles as a safe house in times of flood. I learned about off-the-grid power from a farmer who had recently installed solar panels on the thatch of his mud hut. A local activist taught me about a program that employs women to grow mangrove saplings and replant them on fragile shores. And the lush forests were idyllic (once you looked past the plastic netting designed to keep the tigers in).
Still, it was hard to ignore that these wonderful people and beautiful surroundings are slowly being swallowed by rising seas—just one of the many casualties of climate change. Some islands have already slipped below the water line. In the last decade thousands of villagers have been displaced. The consequences will unfold over decades.
It will be a long goodbye.
And not the only one. So many places, from Micronesia to Miami, are at risk. Part of letting go will involve complex logistics: identifying the places and species to abandon, orchestrating our retreats, planning the resettlement. The other part will be the heartbreak.
How will we deal with the pain of saying goodbye? Will we behave like the orphaned children in psychological studies, the ones who refuse to attach to anyone nice for fear of being abandoned again? Will we stop caring about our favorite coastlines, our storied cities, the world’s cultures, because the possibility of losing them (and knowing we’re to blame) is just too much for us to stomach?
I hope not. If we give up now, we’ll lose what we might have saved with reasonable efforts. And we will have surrendered the reward of knowing and loving the things that matter.
In times like these, we need a shot of Rabindranath Tagore, the Bengali poet and Nobel laureate:
Let me not pray to be sheltered from dangers,
but to be fearless in facing them.
Let me not beg for the stilling of my pain, but
for the heart to conquer it.
Robert Verchick, Gauthier-St. Martin Chair in Environmental Law, Loyola University, New Orleans. Bio.