Estimation of Asymmetric Stochastic Volatility Models: Application to Daily Average Prices of Energy Products

Energy supply and demand, and as a consequence energy prices, are likely to represent one of the biggest challenges of the 21st century. Commodity markets exhibit increased volatility when there is little or no underutilized supply capability to meet natural fluctuations in demand. In the case of energy markets, the large capital requirements and significant lead times associated with energy production and delivery make them more susceptible to the imbalances in supply capability and demand. Energy price volatility has destructive impact on market agents, and this impact is intensified when the prices exhibit asymmetric volatility. This article pursues two aspects of the issue. First we consider general aspects, especially the asymmetric pattern of volatility of daily returns of different types of energy products. Then, we analyze the behaviour of daily returns by using traditional models of volatility that include AGARCH, TGARCH, EGARCH, and ARSV strategies, as well as a threshold asymmetric autoregressive stochastic volatility (TA-ARSV) model that we propose. The energy products considered in this analysis are probably the most relevant energy products for the economic activity of the nations and the economic relations between countries: Crude Oil (OPEC reference basket and London Brent index), Gasoline, Natural Gas, Butane, and Propane. We use spot prices and the time reference ranges from 1986–1993 to 2009 depending on the product.     

Content analysis research method with Nvivo-6 software in a PhD thesis: an approach to the long-term psychological effects on Chilean ex-prisoners survivors of experiences of torture and imprisonment

The aim of this paper is to review the usefulness of the software CAQDAS QSR—Nvivo-6 in a PhD. Thesis, which consisted of finding the long-term psychological effects of experiences of imprisonment and torture for political reasons in their Chilean survivors. For this research, it was created and administered an in-depth interview to 60 survivors, from which outcome was 9900 paragraphs, coded into 784 categories. The software QSR Nvivo-6 threw a report of frequencies, which were compared quantitatively using Pearson’s χ ² square test and cluster analysis. We conclude that the software facilitates the development of qualitative thematic content analysis, simplifying the coding, analysis and display of data. In Addition, it is very useful when working with large quantities of information, promoting the reliability and validity of studies. However, other aspects are also required to ensure the rigor of a qualitative study.     

A linear approximation to the power function of a test

In this paper we obtain a linear approximation to the power function of a test that is very accurate for small sample sizes. This is especially useful for robust tests where not many power functions are available. The approximation is based on the von Mises expansion of the tail probability functional and on the Tail Area Influence Function (TAIF). The goals of the paper are, first to extend the definition of the TAIF to the case of non identically distributed random variables, defining the Partial Tail Area Influence Functions and the Vectorial Tail Area Influence Function; second, to obtain exact expressions for computing these new influence functions; and, finally, to find accurate approximations to the power function, that can be used in the case of non identically distributed random variables. We include some examples of the application of this linear approximation to tests that involve the Huber statistic and also saddlepoint tests, so proving that the approximations apply not only to simple problems but also to complex ones.     

Institutions and human resource practices in European countries

Abstract

Stemming from differences between approaches to new institutionalism, this paper analyses the impact of institutions on the adoption of human resource practices (HRP) in organizations. With this aim in mind, two opposing hypotheses are presented: should configurations of national institutions be related to the actual implementation of HRP by organizations or not? This empirical analysis uses a sample of 29,959 employees who work in organizations established in 27 European countries and takes into account the employees’ perception about the HRP used in their organizations and which affect them. The results support the approach to new institutionalism that emphasizes legitimacy and isomorphism, since these results show empirical regularities when countries are compared. Specifically, a country’s configurations of regulative, normative and cognitive institutions are related to the actual implementation of HRP, such as internal promotion, job participation, job design, work-life balance, job training, assessment and teamwork. These results suggest relevant practical implications for human resource managers and policy-makers.     

Self-employment of immigrants and natives in Sweden – a multilevel analysis

Recent research suggests that self-employment among immigrants is due to a combination of multiple situational, cultural and institutional factors, all acting together. Using multilevel regression and unique data on the entire population of Sweden for the year 2007, this study attempts to quantify the relative importance for the self-employed of embeddedness in ethnic contexts (country of birth) and regional business and public regulatory frameworks (labour market areas). This information indicates whether the layers under consideration are valid constructs of the surroundings that influence individual self-employment. The results show that 10% (women) and 8% (men) of the total variation in individual differences in self-employment can be attributed to the country of birth. When labour market areas are included in the analyses, the share of the total variation increases to 14% for women and 12% for men. The results show that the ethnic context and the economic environment play a minor role in understanding individual differences in self-employment levels. The results can have important implications when planning interventions or other actions focusing on self-employment as public measures to promote self-employment often are based on geographic areas and ethnic contexts.     

A STRUCTURAL RISK‐NEUTRAL MODEL FOR PRICING AND HEDGING POWER DERIVATIVES

We develop a structural risk‐neutral model for energy market modifying along several directions the approach introduced in Aïd et al. In particular, a scarcity function is introduced to allow important deviations of the spot price from the marginal fuel price, producing price spikes. We focus on pricing and hedging electricity derivatives. The hedging instruments are forward contracts on fuels and electricity. The presence of production capacities and electricity demand makes such a market incomplete. We follow a local risk minimization approach to price and hedge energy derivatives. Despite the richness of information included in the spot model, we obtain closed‐form formulae for futures prices and semiexplicit formulae for spread options and European options on electricity forward contracts. An analysis of the electricity price risk premium is provided showing the contribution of demand and capacity to the futures prices. We show that when far from delivery, electricity futures behave like a basket of futures on fuels.     

ON‐THE‐JOB SEARCH,PRODUCTIVITY SHOCKS,AND THE INDIVIDUAL EARNINGS PROCESS*

Individual labor earnings observed in worker panel data have complex, highly persistent dynamics. We investigate the capacity of a structural job search model with on‐the‐job search, wage renegotiation by mutual consent, and i.i.d. productivity shocks to replicate salient properties of these dynamics, such as the covariance structure of earnings, the evolution of individual earnings mean, and variance with the duration of uninterrupted employment, or the distribution of year‐to‐year earnings changes. Structural estimation of our model on a 12‐year panel of highly educated British workers shows that our simple framework produces a dynamic earnings structure that is remarkably consistent with the data.