Markov-switching generalized additive models

We consider Markov-switching regression models, i.e. models for time series regression analyses where the functional relationship between covariates and response is subject to regime switching controlled by an unobservable Markov chain. Building on the powerful hidden Markov model machinery and the methods for penalized B-splines routinely used in regression analyses, we develop a framework for nonparametrically estimating the functional form of the effect of the covariates in such a regression model, assuming an additive structure of the predictor. The resulting class of Markov-switching generalized additive models is immensely flexible, and contains as special cases the common parametric Markov-switching regression models and also generalized additive and generalized linear models. The feasibility of the suggested maximum penalized likelihood approach is demonstrated by simulation and further illustrated by modelling how energy price in Spain depends on the Euro/Dollar exchange rate

Flexible and practical modeling of animal telemetry data: hidden Markov models and extensions

We discuss hidden Markov-type models for fitting a variety of multistate random walks to wildlife movement data. Discrete-time hidden Markov models (HMMs) achieve considerable computational gains by focusing on observations that are regularly spaced in time, and for which the measurement error is negligible. These conditions are often met, in particular for data related to terrestrial animals, so that a likelihood-based HMM approach is feasible. We describe a number of extensions of HMMs for animal movement modeling, including more flexible state transition models and individual random effects (fitted in a non-Bayesian framework). In particular we consider so-called hidden semi-Markov models, which may substantially improve the goodness of fit and provide important insights into the behavioral state switching dynamics. To showcase the expediency of these methods, we consider an application of a hierarchical hidden semi-Markov model to multiple bison movement paths

Defining investment additionality for CDM projects: Practical approaches

The environmental integrity of the CDM under the Kyoto Protocol depends on the possibility to avoid giving emission credits to projects that would have happened anyway. Whether and how ?Investment Additionality? of CDM projects has to be determined is currently part of climate negotiations. We discuss the rationale of companies to invest in projects and analyse possible criteria to determine Investment Additionality from a theoretical point of view. A number of case studies is used to show the implications of the different criteria. The use of a single criterion is not possible, especially due to the importance of non-monetary barriers. However, some criteria are better than others. Moreover, the institutional framework for the selection and application of criteria is very important. Concluding, we suggest a combination of a threshold Internal Rate of Return with a risk factor as primary criterion. To take nonmonetary barriers into account, additional criteria could be used such as the existence of similar privately financed projects in the host country. If no explicit criterion is politically feasible, stringent baseline methodologies could at least capture some aspects of Investment Additionality.Die umweltpolitische Integrität des im Kyoto-Protokoll verankerten CDM hängt davon ab, ob Projekte, die ohnehin stattgefunden hätten, Emissionsgutschriften erhalten können. Ob und wie die ?Zusätzlichkeit der Investition? nachgewiesen werden muss, ist derzeit Bestandteil der Klimaverhandlungen. Wir diskutieren die Entscheidungsgründe, die Firmen zu Investitionen in Projekte bewegen und analysieren mögliche Kriterien für die Bestimmung der Zusätzlichkeit aus einer theoretischen Perspektive. Darüber hinaus werden Fallstudien zur Untersuchung der Auswirkungen der verschiedenen Kriterien herangezogen. Sie zeigen, dass die generelle Beschränkung auf ein einzelnes Kriterium nicht möglich ist. Jedoch sind einige Kriterien besser als andere. Außerdem sind die institutionellen Rahmenbedingungen für die Auswahl und Anwendung der Kriterien sehr wichtig. Zusammenfassend befürworten wir die Kombination eines Schwellenwerts für die interne Ertragsrate mit einem Risikofaktor. Um nicht-monetäre Hindernisse zu berücksichtigen, können zusätzliche Kriterien wie die Existenz von ähnlichen, privat finanzierten Projekten im Gastland überprüft werden. Wenn kein derartiges Kriterium politisch durchsetzbar ist, können strenge Regeln für die Referenzfallbestimmung zumindest einige Aspekte der Zusätzlichkeit einfangen

Evaluation of (non-sink) AIJ projects in developing countries (Ensadec)

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Klimaschutzpolitik - ist das Emissionshandelssystem ein effizientes Mittel zur Emissionsverringerung?

Der Emissionshandel könnte als flexibles Instrument zum Erreichen der Reduktionsziele beitragen. Allerdings sollte er, nach Meinung von Dr. Angelika Zahmt und Matthias Seiche, BUND, mit der ökologischen Steuerreform verknüpft werden. Für Dr. Friedemann Müller, Stiftung Wissenschaft und Politik, kann der Handel nur in Verbindung mit »einer gleichen Verteilung von Emissionsrechten pro Kopf« ein Ansatz zur Lösung des Klimaproblems sein. Auch nach Ansicht von Dr. Hermann E. Ott und Thomas Langrock, Wuppertal Institut, sprechen gute Gründe für einen internationalen Emissionshandel. Für Prof. Dr. Wolfgang Ströbele, Universität Münster, ist zur Lösung des Emissionsproblems der konkrete EU-Richtlinienvorschlag »wenig nützlich«.Umweltzertifikat; Umweltbelastung; Klimaschutz; EU-Recht

Klimaschutzpolitik - ist das Emissionshandelssystem ein effizientes Mittel zur Emissionsverringerung?

Der Emissionshandel könnte als flexibles Instrument zum Erreichen der Reduktionsziele beitragen. Allerdings sollte er, nach Meinung von Dr. Angelika Zahmt und Matthias Seiche, BUND, mit der ökologischen Steuerreform verknüpft werden. Für Dr. Friedemann Müller, Stiftung Wissenschaft und Politik, kann der Handel nur in Verbindung mit »einer gleichen Verteilung von Emissionsrechten pro Kopf« ein Ansatz zur Lösung des Klimaproblems sein. Auch nach Ansicht von Dr. Hermann E. Ott und Thomas Langrock, Wuppertal Institut, sprechen gute Gründe für einen internationalen Emissionshandel. Für Prof. Dr. Wolfgang Ströbele, Universität Münster, ist zur Lösung des Emissionsproblems der konkrete EU-Richtlinienvorschlag »wenig nützlich«

Statistical modelling of individual animal movement: an overview of key methods and a discussion of practical challenges

With the influx of complex and detailed tracking data gathered from electronic tracking devices, the analysis of animal movement data has recently emerged as a cottage industry among biostatisticians. New approaches of ever greater complexity are continue to be added to the literature. In this paper, we review what we believe to be some of the most popular and most useful classes of statistical models used to analyse individual animal movement data. Specifically, we consider discrete-time hidden Markov models, more general state-space models and diffusion processes. We argue that these models should be core components in the toolbox for quantitative researchers working on stochastic modelling of individual animal movement. The paper concludes by offering some general observations on the direction of statistical analysis of animal movement. There is a trend in movement ecology towards what are arguably overly complex modelling approaches which are inaccessible to ecologists, unwieldy with large data sets or not based on mainstream statistical practice. Additionally, some analysis methods developed within the ecological community ignore fundamental properties of movement data, potentially leading to misleading conclusions about animal movement. Corresponding approaches, e.g. based on Lévy walk-type models, continue to be popular despite having been largely discredited. We contend that there is a need for an appropriate balance between the extremes of either being overly complex or being overly simplistic, whereby the discipline relies on models of intermediate complexity that are usable by general ecologists, but grounded in well-developed statistical practice and efficient to fit to large data sets

Optical Cherenkov radiation by cascaded nonlinear interaction: an efficient source of few-cycle energetic near- to mid-IR pulses

When ultrafast noncritical cascaded second-harmonic generation of energetic femtosecond pulses occur in a bulk lithium niobate crystal optical Cherenkov waves are formed in the near- to mid-IR. Numerical simulations show that the few-cycle solitons radiate Cherenkov (dispersive) waves in the \lambda=2.2-4.5\mic range when pumping at \lambda_1=1.2-1.8\mic. The exact phase-matching point depends on the soliton wavelength, and we show that a simple longpass filter can separate the Cherenkov waves from the solitons. The Cherenkov waves are born few-cycle with an excellent Gaussian pulse shape, and the conversion efficiency is up to 25%. Thus, optical Cherenkov waves formed with cascaded nonlinearities could become an efficient source of energetic near- to mid-IR few-cycle pulses.Comment: Extended version of Nonlinear Optics 2011 contribution http://www.opticsinfobase.org/abstract.cfm?URI=NLO-2011-NTuA7. Submitted for Optics Express special issue for NLO conferenc