The evaluation of forest crop damages due to climate change. An application of Dempster–Shafer method

In order to assess damage risk caused by climate change in forest areas, Dempster–Shafer theory of evidence and fuzzy measures were applied to develop a framework for the estimation of economic forest damage. According to the definition of risk supported by the Intergovernmental Panel on Climate Change, a function of hazard and resilience lines of evidence was defined. The results of the hazard and resilience assessment were used to develop an economic framework based on Faustmann studies. The evaluation model, implemented through a spatial analysis procedure, was carried out linking Faustmann formula with hazard and resilience raster maps. The model permitted to estimate in monetary terms two possible costs to be supported: the first one is expressed as the expected damage to the forest crop on the basis of the current obtainable woody assortments and the second one referred to the potential expenses to pay in order to mitigate the risk. Finally, the framework was tested on an area of central Italy (Tuscany region).     

Analysis of ultra-high-frequency financial data using advanced Fourier transforms

This paper presents a novel application of advanced methods from Fourier analysis to the study of ultra-high-frequency financial data. The use of Lomb–Scargle Fourier transform, provides a robust framework to take into account the irregular spacing in time, minimising the computational effort. Likewise, it avoids complex model specifications (e.g. ACD or intensity models) or resorting to traditional methods, such as (linear or cubic) interpolation and regular resampling, which not only cause artifacts in the data and loss of information, but also lead to the generation and use of spurious information.     

Impact is not just volatility

With a simple scaling argument we show empirically that impact growing as the square-root of trading volume has nothing to do with diffusion price changes growing as the square root of time     

WORK HISTORIES AND LIFETIME UNEMPLOYMENT

A long-standing question in economics is how important unobserved differences across workers are for explaining unemployment. I revisit this topic using variation in lifetime unemployment across workers in U.S. data. A comparison of workers often unemployed with the rest shows that although differences in job-finding rates increase over the course of a career, differences in job-separation rates are large right from the start. I develop a directed search model with symmetric unobserved heterogeneity, in which agents learn workers' types from their labor market histories, to rationalize these findings. The model cannot match the data if unobserved heterogeneity is neglected.     

PERIODICITIES OF FOREIGN EXCHANGE MARKETS AND THE DIRECTIONAL CHANGE POWER LAW

This paper utilizes advanced methods from Fourier analysis in order to describe periodicities in financial ultrahigh frequency foreign exchange data. The Lomb–Scargle Fourier transform is used to take into account the irregularity in spacing in the time domain. It provides a natural framework for the power spectra of different inhomogeneous time‐series processes to be easily and quickly estimated. Furthermore, an event‐based approach in intrinsic time based on a power‐law relationship is employed using different event thresholds to filter the foreign exchange tick‐data. The calculated spectral density demonstrates that the price process in intrinsic time contains different periodic components for directional changes, especially in the medium–long term, implying the existence of stylized facts of ultrahigh frequency data in the frequency domain. Copyright © 2013 John Wiley & Sons, Ltd.     

Spillovers,product innovation and R&D cooperation: a theoretical model

ABSTRACT

We analyze the impact of post-innovation knowledge spillovers on firms’ decisions to invest and cooperate in R&D, forming a research joint venture (RJV). We study the case of two potential investors involved in a non-tournament stochastic competition for developing a new but imitable product. We propose a theoretical model where cooperation may emerge as a subgame perfect Nash equilibrium of a three-stage game. In the first stage, firms decide whether to cooperate; in the second, they decide whether to invest; and in the third, they compete. We show that firms cooperate in R&D when the spillovers are high enough and the fixed costs associated with R&D activities are low enough; however, our analysis suggests that forming an RJV may not always be socially optimal, and subsidizing R&D cooperation may not be efficient. We propose an optimal scheme of subsidies, which should be designed according to the intensity of the spillovers, the level of the R&D costs, and the probability of innovation success. Finally, we show that in the case of mergers the private incentive to invest is maximized, and firms may not need public subsidies to cooperate. When subsidies are costly, not hindering mergers may be the second-best solution.