The Economics of Spruce Budworm Outbreaks in the Lake States: An Overview

Economic effects of spruce budworm outbreaks in the Lake States were examined. The recent outbreak caused spruce and fir mortality on 420 thousand ha (I.OS million acres) of commercial forest land in the Lake States. Two models of Lake States spruce-fir markets were developed. A Static Economic Model established the nature of the Lake States spruce-fir market and a Comparative Static Model examined changes brought about by spruce budworm outbreaks. Outbreaks result in short-run supply shifts which probably decrease total revenue to stumpage owners but do not affect demand. The magnitude of long-run impacts were dependent on developing Lake States markets and forest management techniques. Further research is necessary on the value of short-run losses to stumpage owners so that the costs of forest management can be compared with outbreak losses. Long-run shifts in demand can be facilitated by attracting new industry to the area, developing new markets for the spruce-fir resource, and demonstrating that the spruce-fir resource can provide a continuous fiber source in the future. These shifts would provide the price incentives that land managers require to undertake intensive forest management. Research on the development of new markets for the spruce-fir resource is needed. As markets develop, the long-run impacts become less severe. Technology transfer programs already exist to aid land managers in developing management strategies to increase yields of spruce-fir and minimize outbreak impact

Whose incentives? The evolution of inheritance practices, intergenerational conflict, and women’s control over land in rural Kenya

Land related investment decisions are shaped by both the formal and informal institutions governing land tenure and acquisition. In the case of agricultural Kikuyu households in Kenya, we show that the inheritance practice of uncertain allocation in conjunction with the principle of equal division among heirs reduces long-term investments in land among potential heirs. This apparent inefficiency is explained by intergenerational power dynamics within the household, as the inheritance practice allows parents to shift the investment incentives facing heirs in their favor. This analytical framework is also used to illustrate that despite legislation formalizing women’s rights to property, control over land continues to follow the informal traditional patrilineal system in important ways.Inheritance, agriculture, Kenya

AN EQUILIBRIUM ANALYSIS OF ANTIBIOTICS USE AND REPLANTING DECISIONS IN APPLE PRODUCTION

Antibiotics are used in fruit production to control fire blight, a bacterial disease of fruit trees that causes yield losses and eventually tree death. Fearing the development of widespread antibiotic resistance, scientists and public health officials are becoming increasingly concerned about antibiotics use in agriculture. A framework is developed for assessing the impacts of changes in tree damage risk following a ban on antibiotics use in the apple industry. Allowing for entry and exit, a long-run analysis of replanting dates and equilibrium prices is provided, as well as an estimate of the welfare impacts of a ban on antibiotics.Crop Production/Industries,

Changes in growth of tropical forests: evaluating potential biases

Over the past century almost every ecosystem on Earth has come under the influence of changes in atmospheric composition and climate caused by human activity. Tropical forests are among the most productive and extensive ecosystems, and it has been hypothesized that both the dynamics and biomass of apparently undisturbed, old-growth tropical forests have been changing in response to atmospheric changes. Long-term forest sample plots are a critical tool in detecting and monitoring such changes, and our recent analysis of pan-tropical-forest plot data has suggested that the biomass of tropical forests has been increasing, providing a modest negative feedback on the rate of accumulation of atmospheric CO2. However, it has been argued that some of these old forest plot data sets have significant problems in interpretation because of the use of nonstandardized methodologies. In this paper we examine the extent to which potential field methodological errors may bias estimates of total biomass change by detailed examination of tree-by-tree records from up to 120 Neotropical plots to test predictions from theory. Potential positive biases on measurements of biomass change include a bias in site selection, tree deformities introduced by the measurement process, poor methodologies to deal with tree deformities or buttresses, and nonrecording of negative growth increments. We show that, while it is important to improve and standardize methodologies in current and future forest-plot work, any systematic errors introduced by currently identified biases in past studies are small and calculable. We conclude that most tropical-forest plot data are of useful quality, and that the evidence does still weigh conclusively in favor of a recent increase of biomass in old-growth tropical forests

Axiomatic Interpretability for Multiclass Additive Models

Generalized additive models (GAMs) are favored in many regression and binary classification problems because they are able to fit complex, nonlinear functions while still remaining interpretable. In the first part of this paper, we generalize a state-of-the-art GAM learning algorithm based on boosted trees to the multiclass setting, and show that this multiclass algorithm outperforms existing GAM learning algorithms and sometimes matches the performance of full complexity models such as gradient boosted trees. In the second part, we turn our attention to the interpretability of GAMs in the multiclass setting. Surprisingly, the natural interpretability of GAMs breaks down when there are more than two classes. Naive interpretation of multiclass GAMs can lead to false conclusions. Inspired by binary GAMs, we identify two axioms that any additive model must satisfy in order to not be visually misleading. We then develop a technique called Additive Post-Processing for Interpretability (API), that provably transforms a pre-trained additive model to satisfy the interpretability axioms without sacrificing accuracy. The technique works not just on models trained with our learning algorithm, but on any multiclass additive model, including multiclass linear and logistic regression. We demonstrate the effectiveness of API on a 12-class infant mortality dataset.Comment: KDD 201

Global aging: emerging challenges

This repository item contains a single issue of The Pardee Papers, a series papers that began publishing in 2008 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future. The Pardee Papers series features working papers by Pardee Center Fellows and other invited authors. Papers in this series explore current and future challenges by anticipating the pathways to human progress, human development, and human well-being. This series includes papers on a wide range of topics, with a special emphasis on interdisciplinary perspectives and a development orientation.Aging policy frameworks were devised during a demographic and economic context in which population aging seemed confined to wealthy nations. These countries could afford retirement policies that supported older workers, decreased unemployment among younger workers, and decreased family pressure to provide old age care. This calculation was based in part on failure to anticipate three demographic trends: continual decline in fertility below replacement rate, continual gains in longevity, and the rise of population aging in poor and “under-developed” countries. These three trends now fuel a sense of crisis. In the global North, there is fear that increasing numbers of older adults will deplete state pension and health care systems. In the global South, the fear is that population aging coupled with family breakdown” requires such state intervention. Natural disaster metaphors, such as “agequake” and “age-tsunami,” illustrate fears of a “graying globe” in which population aging implies population decay and economic destruction. Yet, global aging trends develop over decades and are not easily reversed. Longer-range trends can be addressed through revising policy frameworks to incorporate how growing old is moving from global exception to expectation. Alexandra Crampton was a 2008–2009 Postdoctoral Fellow at the Frederick S. Pardee Center for the Study of the Longer-Range Future and is currently Assistant Professor in the Department of Social and Cultural Sciences at Marquette University. Her scholarship and teaching bring an anthropological perspective to theoretical and practical questions on aging, social welfare policy, social work practice, negotiation, and alternative dispute resolution. She has presented her work for the American Anthropological Association, the Gerontological Society of America, the Council on Social Work Education, and the Society for Social Work Research. She holds a joint PhD in Social Work and Anthropology from the University of Michigan

Pricing and Hedging GLWB in the Heston and in the Black-Scholes with Stochastic Interest Rate Models

Valuing Guaranteed Lifelong Withdrawal Benefit (GLWB) has attracted significant attention from both the academic field and real world financial markets. As remarked by Forsyth and Vetzal the Black and Scholes framework seems to be inappropriate for such long maturity products. They propose to use a regime switching model. Alternatively, we propose here to use a stochastic volatility model (Heston model) and a Black Scholes model with stochastic interest rate (Hull White model). For this purpose we present four numerical methods for pricing GLWB variables annuities: a hybrid tree-finite difference method and a hybrid Monte Carlo method, an ADI finite difference scheme, and a standard Monte Carlo method. These methods are used to determine the no-arbitrage fee for the most popular versions of the GLWB contract, and to calculate the Greeks used in hedging. Both constant withdrawal and optimal withdrawal (including lapsation) strategies are considered. Numerical results are presented which demonstrate the sensitivity of the no-arbitrage fee to economic, contractual and longevity assumptions