A Model of Real Estate Sales as a Career Choice

This article develops a model of the probability that individuals choose careers in real estate sales. The model is estimated using Census data. Females are found to be significantly more likely than males to enter the field. For males, the probability of entering the field grows with schooling up through four years of college, and declines thereafter. For females, the probability falls with increased schooling beyond high school. Real estate sales is a career that is more appealing to both males and females with more labor market experience. For females, the probability of choosing a real estate career rises at a decreasing rate with experience. For males, the probability grows at an increasing rate. Both females and males are very responsive in their career choice decisions to changes in real earnings. The supply price elasticity, evaluated at the mean, is estimated to be +3.18 for males and +2.76 for females.

Efficient tilings of de Bruijn and Kautz graphs

Kautz and de Bruijn graphs have a high degree of connectivity which makes them ideal candidates for massively parallel computer network topologies. In order to realize a practical computer architecture based on these graphs, it is useful to have a means of constructing a large-scale system from smaller, simpler modules. In this paper we consider the mathematical problem of uniformly tiling a de Bruijn or Kautz graph. This can be viewed as a generalization of the graph bisection problem. We focus on the problem of graph tilings by a set of identical subgraphs. Tiles should contain a maximal number of internal edges so as to minimize the number of edges connecting distinct tiles. We find necessary and sufficient conditions for the construction of tilings. We derive a simple lower bound on the number of edges which must leave each tile, and construct a class of tilings whose number of edges leaving each tile agrees asymptotically in form with the lower bound to within a constant factor. These tilings make possible the construction of large-scale computing systems based on de Bruijn and Kautz graph topologies.Comment: 29 pages, 11 figure

The Dynamics of Metropolitan Housing Prices

This article is the winner of the Innovative Thinking ‘‘Thinking Out of the Box’’ manuscript prize (sponsored by the Homer Hoyt Advanced Studies Institute) presented at the 2001 American Real Estate Society Annual Meeting. This study examines the dynamics of real housing price appreciation in 130 metropolitan areas across the United States. The study finds that real housing price appreciation is strongly influenced by the growth of population and real changes in income, construction costs and interest rates. The study also finds that stock market appreciation imparts a strong current and lagged wealth effect on housing prices. Housing appreciation rates also are found to vary across areas because of location-specific fixed-effects; these fixed effects represent the residuals of housing price appreciation attributable to location. The magnitudes of the fixed-effects in particular cities are positively correlated with restrictive growth management policies and limitations on land availability.

Gaussian Process Morphable Models

Statistical shape models (SSMs) represent a class of shapes as a normal distribution of point variations, whose parameters are estimated from example shapes. Principal component analysis (PCA) is applied to obtain a low-dimensional representation of the shape variation in terms of the leading principal components. In this paper, we propose a generalization of SSMs, called Gaussian Process Morphable Models (GPMMs). We model the shape variations with a Gaussian process, which we represent using the leading components of its Karhunen-Loeve expansion. To compute the expansion, we make use of an approximation scheme based on the Nystrom method. The resulting model can be seen as a continuous analogon of an SSM. However, while for SSMs the shape variation is restricted to the span of the example data, with GPMMs we can define the shape variation using any Gaussian process. For example, we can build shape models that correspond to classical spline models, and thus do not require any example data. Furthermore, Gaussian processes make it possible to combine different models. For example, an SSM can be extended with a spline model, to obtain a model that incorporates learned shape characteristics, but is flexible enough to explain shapes that cannot be represented by the SSM. We introduce a simple algorithm for fitting a GPMM to a surface or image. This results in a non-rigid registration approach, whose regularization properties are defined by a GPMM. We show how we can obtain different registration schemes,including methods for multi-scale, spatially-varying or hybrid registration, by constructing an appropriate GPMM. As our approach strictly separates modelling from the fitting process, this is all achieved without changes to the fitting algorithm. We show the applicability and versatility of GPMMs on a clinical use case, where the goal is the model-based segmentation of 3D forearm images

The Emergence of Neutrality

This Article traces two interwoven jurisprudential genealogies. The first of these focuses on the emergence of neutrality in speech and press doctrine. Content and viewpoint neutrality are now the bedrock principles of modern First Amendment law. Yet the history of these concepts is largely untold and otherwise misunderstood. Scholars usually assume that expressive-freedom doctrine was mostly undeveloped before the early twentieth century and that neutrality was central to its modern rebirth. But this view distorts and sometimes even inverts historical perspectives. For most of American history, the governing paradigm of expressive freedom was one of limited toleration, focused on protecting speech within socially defined boundaries. The modern embrace of content and viewpoint neutrality, it turns out, occurred only in the 1960s as the Supreme Court merged earlier strands of rights jurisprudence in novel ways. The emergence of neutrality, this Article shows, was more gradual, more contested, and more contingent than we now assume. Recovering this history reveals the novelty of the modern neutrality paradigm and casts new light on the history of other First Amendment concepts, like prior restraints, low-value speech, and overbreadth.To understand these developments, it is necessary to trace a second doctrinal genealogy that focuses on the concept of fundamental rights. Older views of expressive freedom were embedded in a different conceptual framework for thinking about rights. And once again, the role of neutrality within this tradition was radically different. Today, neutrality is ubiquitous in rights discourse, reflecting the prevailing view that rights are domains in which people can make their own moral choices. Thus defined, rights need not be absolute, but the government must at least maintain neutrality with respect to values. As this Article reveals, however, this neutrality-based view of rights emerged well into the twentieth century, reflecting a transmogrified synthesis of earlier ideas.Recovering these older paradigms powerfully illustrates how deeply our current perspectives shape the way that we view the Constitution. Principles that appear to be inherent to the very idea of expressive freedom or the very idea of rights, it turns out, are refracted through a modern lens. Integrating history into rights jurisprudence thus poses a substantial and unresolved challenge, warranting further engagement by scholars and judges. On its own, history cannot dictate whether our approach to rights needs adjustment. But it can refocus attention on values and choices that modern doctrine too often ignores

Natural Rights and the First Amendment

The Supreme Court often claims that the First Amendment reflects an original judgment about the proper scope of expressive freedom. After a century of academic debate, how­ ever, the meanings of speech and press freedoms at the Founding remain remarkably hazy. Many scholars, often pointing to Founding Era sedition prosecutions, emphasize the limited scope of these rights. Others focus on the libertarian ideas that helped shape opposition to the Sedition Act of 1798. Still more claim that speech and press freedoms lacked any commonly accepted meaning. The relationship between speech and press freedoms is contested, too. Most scholars view these freedoms as equivalent, together enshrining a freedom of expression. But others assert that the freedom of speech, unlike press freedom, emerged from the legislative privilege of speech and debate, thus providing more robust protection for political speech

Natural Rights and the First Amendment

The Supreme Court often claims that the First Amendment reflects an original judgment about the proper scope of expressive freedom. After a century of academic debate, however, the meanings of speech and press freedoms at the Founding remain remarkably hazy. Many scholars, often pointing to Founding Era sedition prosecutions, emphasize the limited scope of these rights. Others focus on the libertarian ideas that helped shape opposition to the Sedition Act of 1798. Still more claim that speech and press freedoms lacked any commonly accepted meaning. The relationship between speech and press freedoms is contested, too. Most scholars view these freedoms as equivalent, together enshrining a freedom of expression. But others assert that the freedom of speech, unlike press freedom, emerged from the legislative privilege of speech and debate, thus providing more robust protection for political speech. This Article argues that Founding Era elites shared certain understandings of speech and press freedoms, as concepts, even when they divided over how to apply those concepts. In particular, their approach to expressive freedom was grounded in a multifaceted understanding of natural rights that no longer survives in American constitutional thought. Speech and press freedoms referred, in part, to natural rights that were expansive in scope but weak in their legal effect, allowing for restrictions of expression to promote the public good. In this respect, speech and press freedoms were equivalent concepts with highly contestable implications that depended on calculations of the public good. But expressive freedom connoted more determinate legal protections as well. The liberty of the press, for instance, often referred specifically to the rule against press licensing, while the freedom of speaking, writing, and publishing ensured that well-intentioned statements of one’s views were immune from governmental regulation. In this respect, speech and press freedoms carried distinct meanings. Much of our modern confusion stems from how the Founders—immersed in their own constitutional language—silently shifted between these complementary frames of reference. This framework significantly reorients our understanding of the history of speech and press freedoms by recognizing the multifaceted meanings of these concepts, and it raises challenging questions about how we might use that history today. Various interpretive theories—including ones described as “originalist”—might incorporate this history in diverse ways, with potentially dramatic implications for a host of First Amendment controversies. Most fundamentally, however, history undercuts the Supreme Court’s recent insistence that the axioms of modern doctrine inhere in the Speech Clause itself, with judges merely discovering—not crafting—the First Amendment’s contours and boundaries

Turning the Endangered Species Act inside Out

Within a week, both the Fifth and D.C. Circuits upheld the takings prohibitions of the Endangered Species Act (ESA) of 1973, as applied to species found only in single states, against Commerce Clause challenges. Both cases reach the same result, but the legal analysis used to get there could hardly be more different. In GDF Realty, the Fifth Circuit found the requisite substantial impact on commerce by treating the species themselves as commodities and aggregating the economic impact of all endangered species takings . The D.C. Circuit, by contrast, held in Rancho Viejo that the true object of ESA regulation is not endangered species, but the commercial development that threatens them, which plainly falls within Congress\u27s powers to regulate under the Commerce Clause. The two courts saved the threatened arroyo toads and subterranean invertebrates, but they read the Endangered Species Act as if it were two different statutes.This curious divergence can only be understood in light of the unsettled state of Commerce Clause jurisprudence following United States v. Lopez and United States v. Morrison. Those two decisions upended fifty years of conventional wisdom about the limits on Congress\u27s power under the Commerce Clause – namely, that there were effectively none – and left lower courts with an uncertain new framework to apply. Of the two cases considered here, Rancho Viejo represents the abler attempt to square the ESA with the new Commerce Clause doctrine, because its analysis is more objective than GDF Realty\u27s and more clearly satisfies the strictures of Lopez and Morrison. But like GDF Realty, Rancho Viejo must present the ESA\u27s impact on commerce, which is peripheral in the statutory design, as the Act\u27s core object – must turn the ESA inside out, so to speak – in order to justify it under the Commerce Clause. This cramped conception of the statute does not convincingly justify all of its applications. The shortcomings of Rancho Viejo do not represent sloppiness on the part of the D.C. Circuit, however. Instead, they reflect the failure of the Lopez and Morrison framework to meet the Supreme Court\u27s stated aspiration to distinguish between what is truly national and what is truly local