Challenges in approximating the Black and Scholes call formula with hyperbolic tangents

Decisions in Economics and Finance - In this paper, we introduce the concept of standardized call function and we obtain a new approximating formula for the Black and Scholes call function through...     

Consumption and Portfolio Choice over the Life Cycle

This article solves a realistically calibrated life cycle modelof consumption and portfolio choice with non-tradable laborincome and borrowing constraints. Since labor income substitutesfor riskless asset holdings, the optimal share invested in equitiesis roughly decreasing over life. We compute a measure of theimportance of human capital for investment behavior. We findthat ignoring labor income generates large utility costs, whilethe cost of ignoring only its risk is an order of magnitudesmaller, except when we allow for a disastrous labor incomeshock. Moreover, we study the implications of introducing endogenousborrowing constraints in this incomplete-markets setting.     

Extreme Value Theory and Statistics of Univariate Extremes: A Review

Statistical issues arising in modelling univariate extremes of a random sample have been successfully used in the most diverse fields, such as biometrics, finance, insurance and risk theory. Statistics of univariate extremes (SUE), the subject to be dealt with in this review paper, has recently faced a huge development, partially because rare events can have catastrophic consequences for human activities, through their impact on the natural and constructed environments. In the last decades, there has been a shift from the area of parametric SUE, based on probabilistic asymptotic results in extreme value theory, towards semi‐parametric approaches. After a brief reference to Gumbel's block methodology and more recent improvements in the parametric framework, we present an overview of the developments on the estimation of parameters of extreme events and on the testing of extreme value conditions under a semi‐parametric framework. We further discuss a few challenging topics in the area of SUE. © 2014 The Authors. International Statistical Review © 2014 International Statistical Institute     

Asymptotic comparison at optimal levels of reduced‐bias extreme value index estimators

In this article we are interested in the asymptotic comparison, at optimal levels, of a set of semi‐parametric reduced‐bias extreme value (EV) index estimators, valid for a wide class of heavy‐tailed models, underlying the available data. Again, as in the classical case, there is not any estimator that can always dominate the alternatives, but interesting clear‐cut patterns are found. Consequently, and in practice, a suitable choice of a set of EV index estimators will jointly enable us to better estimate the EV index γ, the primary parameter of extreme events.     

Capital services estimates in Portuguese industries, 1977–2003

This paper presents capital services estimates for 26 Portuguese industries for the 1977–2003 period. The estimation procedure follows an integrated approach under which the flows of capital services are approximated as a proportion of the capital stock converted into standard efficiency units. Our findings suggest a close proximity between the evolution of capital flows and the observed fluctuations of Portuguese macroeconomic growth. TFP growth estimates based on growth accounting reveal, furthermore, a very disappointing performance of the Portuguese economy during the period under study, with an average annual rate of TFP growth of 0.8% being observed. Performance varies across industries, but the bulk of activities show very modest rates of TFP growth.     

Design principles of hybrid approaches in new product development: a systematic literature review

Setting the right approach for new product development (NPD) in the presence of uncertainty remains an ongoing debate in innovation management. Stage-gate systems (SGS) and agile methodology (AM) are the dominant approaches. Recently, hybrid approaches (combining SGS and AM) have been proposed. Although these hybrid approaches represent a significant development in NPD, combining them without considering their design principles might lead to contradictory and competing conceptual formulations, thus increasing the difficulty of comparison among studies. Moreover, scholars and practitioners may struggle to understand when, why and how a certain configuration of the NPD process provides the right response to different manifestations of uncertainty. The current literature faces problems regarding the clarity of design principles (e.g. flexibility and adaptability), and this has led to research gaps concerning the uncertainty contingency and outcomes of hybrid approaches. This study combines bibliometric and content analyses to identify four design parameters and principles of NPD hybrid approaches: flexibility, adaptability, velocity and integration. Our findings might help advance the development and comparison of different hybrid approaches.     

Multi-level governance for sustainable innovation in smart communities: an ecosystems approach

International Entrepreneurship and Management Journal - This paper analyses the TrentoSmartCity project to redefine Trento (an Italian municipality) as a smart community according to an ecosystems...     

Analysing reviews in the Web 2.0: Small and medium hotels in Portugal

This study presents a characterisation of online reviews for small and medium hotels (SMH) in Portugal. We collected and analysed 1500 online reviews from 50 SMH. The findings show that room, staff and location were the concepts most frequently appeared in the reviews, with cleanliness, friendliness, helpfulness, and centrality of position the terms most frequently used to qualify the concepts. This study points out the main features which SMH managers should prioritize.