Spatial interpolation of high-frequency monitoring data

Climate modelers generally require meteorological information on regular grids, but monitoring stations are, in practice, sited irregularly. Thus, there is a need to produce public data records that interpolate available data to a high density grid, which can then be used to generate meteorological maps at a broad range of spatial and temporal scales. In addition to point predictions, quantifications of uncertainty are also needed. One way to accomplish this is to provide multiple simulations of the relevant meteorological quantities conditional on the observed data taking into account the various uncertainties in predicting a space-time process at locations with no monitoring data. Using a high-quality dataset of minute-by-minute measurements of atmospheric pressure in north-central Oklahoma, this work describes a statistical approach to carrying out these conditional simulations. Based on observations at 11 stations, conditional simulations were produced at two other sites with monitoring stations. The resulting point predictions are very accurate and the multiple simulations produce well-calibrated prediction uncertainties for temporal changes in atmospheric pressure but are substantially overconservative for the uncertainties in the predictions of (undifferenced) pressure.Comment: Published in at http://dx.doi.org/10.1214/08-AOAS208 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

State Fish Stocking Programs at Risk: Takings Under the Endangered Species Act

Part I of this article provides a brief background to fish stocking practices in the United States, including a discussion of beneficial fish stocking practices, as well as some of the allegations surrounding the detrimental effects. Part II of this article provides some necessary background on section 9 of the ESA, the “actual injury” prong, the “significant impairment” prong, and their application to fish stocking. Part III of this article sets forth recommendations for future clarification and increased consistency on these issues. Specifically, this article supports the use of two rules that can help reconcile the uncertain landscape surrounding a taking based on habitat modification. First, “actual injury” should be found where there is injury to either an individual or a population of protected species. Second, the degree of proof required to establish an “injury” where essential behaviors are impaired should be bifurcated into two tests, depending on which behavioral pattern is being adversely affected. Together, these rules can bring resolution not only to scenarios like fish stocking, but also to other future fact patterns scrutinized under the habitat modification analysis. Part IV of this article demonstrates how application of these rules to states can further the goals of the ESA, both through voluntary reevaluation of fish stocking programs, and through application for an Incidental Take Permit and corresponding Habitat Conservation Plan. These rules can provide two different paths to the same goal: to minimize adverse impacts to endangered and threatened species

Spatial variation of total column ozone on a global scale

The spatial dependence of total column ozone varies strongly with latitude, so that homogeneous models (invariant to all rotations) are clearly unsuitable. However, an assumption of axial symmetry, which means that the process model is invariant to rotations about the Earth's axis, is much more plausible and considerably simplifies the modeling. Using TOMS (Total Ozone Mapping Spectrometer) measurements of total column ozone over a six-day period, this work investigates the modeling of axially symmetric processes on the sphere using expansions in spherical harmonics. It turns out that one can capture many of the large scale features of the spatial covariance structure using a relatively small number of terms in such an expansion, but the resulting fitted model provides a horrible fit to the data when evaluated via its likelihood because of its inability to describe accurately the process's local behavior. Thus, there remains the challenge of developing computationally tractable models that capture both the large and small scale structure of these data.Comment: Published at http://dx.doi.org/10.1214/07-AOAS106 in the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

The Diversity of Debt Crises in Europe

The foreign debts of the European countries are at the core of the current crises. Generally, the crises are attributed to government budget deficits in excess of the values stated in the Stability and Growth Pact (SGP)/Maastricht treaty. Proposals for reform generally involve increasing the powers of the European Union to monitor fiscal policies of the national governments and increasing bank regulation. My article is concerned with the following issues. [Q1] How can one explain the inter country differences in the debt crisis in Europe? Is there a single explanation, cause? [Q2] Specifically, were the crises due to government budget deficits or to the private sector? The answer will determine what is the appropriate policy to prevent a recurrence. [Q3] The Stability and Growth Pact/Maastricht Treaty and the European Union focused upon rules concerning government debt ratios and deficit ratios. They ignored the problem of “excessive” debt ratios in the private sector that led to a crisis in the financial markets. Neither the markets nor the Central Banks anticipated the crises until it was too late. My basic questions are: What is an “excessive” private sector debt ratio that is likely to lead to a crisis? What are theoretically based, not empirical ad hoc, Early Warning Signals (EWS) of debt crises? The answers determine to a large extent how one should evaluate proposals for economic reform, to avert future crises?European debt crisis, excess debt, early warning signals, domestic housing sector, government deficit debt

A Critique of the Literature on the US Financial Debt Crisis

A healthy financial system encourages the efficient allocation of capital and risk. The collapse of the house price bubble led to the financial crisis that started in 2007. There is a large empirical literature concerning the relation between asset price bubbles and financial crises. I evaluate the key studies with the respect to the following questions. To what extent do the empirical relations in the existing literature help to identify asset price bubbles ex-ante or ex-post? Do the empirical studies have theoretical foundations? On the basis of that critique, I explain why the application of stochastic optimal control (SOC)/dynamic risk management is a much more effective approach to determine the optimal degree of leverage, the optimum and excessive risk and the probability of a debt crisis. The theoretically founded early warning signals of a crisis are shown to be superior, in general, to those empirical relations in the literature. Moreover the SOC analysis provides a theoretical explanation of the extent that the empirical measures in the literature can be useful.stochastic optimal control, mortgage and financial crises, Ito equation, optimal dynamic risk management, warning signals of crisis, optimal leverage and debt ratios, Congressional Oversight Panel, Case-Shiller index