Modelling conditional heteroskedasticity: Application to the “IBEX-35” stock-return index

This paper compares alternative time-varying volatility models for daily stock-returns using data from Spanish equity index IBEX-35. Specifically, we estimate a parametric family of models of generalized autoregressive heteroskedasticity (which nests the most popular symmetric and asymmetric GARCH models), a semiparametric GARCH model, the generalized quadratic ARCH model, the stochastic volatility model, the Poisson Jump Diffusion model and, finally, a nonparametric model. Those models which use conditional standard deviation (specifically, TGARCH and AGARCH models) produce better fits than all other GARCH models. We also compare the within sample predictive power of all models using a standard efficiency test. Our results show that the asymmetric behaviour of responses is a statistically significant characteristic of these data. Moreover, we observe that specifications with a distribution which allows for fatter tails than a normal distribution do not necessarily outperform specifications with a normal distribution.     

Micro-behaviors and structural properties of knowledge networks: toward a ‘one size fits one’ cluster policy

The economic returns of cluster policies have been recently called into question. Based on a “one size fits all” approach consisting in boosting R&D collaborations and reinforcing network density, cluster policies are suspected to have failed in reaching their objectives. The paper proposes to go back to the micro foundations of clusters in order to disentangle the links between the long run performance of clusters and their structural properties. We use a simple agent-based model to shed light on how individual motives to build knowledge relationships can give rise to emerging structures with different properties, which imply different innovation and renewal capacities. The simulation results are discussed in a micro-macro perspective, and motivate suggestions to reorient cluster policy guidelines towards more targeted public-funded incentives for R&D collaboration.     

The use of Zostavax in Spain: the economic case for vaccination of individuals aged 50 years and older

Background Population aging brings up a number of health issues, one of which is an increased incidence of herpes zoster (HZ) and its complication, post-herpetic neuralgia (PHN). Zostavax vaccine has recently become available to prevent HZ and PHN. This study evaluates the cost-effectiveness of vaccination against HZ in Spain considering a vaccination of the population aged 50 years and older and comparing this to the current situation where no vaccination is being administered.

Methods An existing, validated, and published economic model was adapted to Spain using relevant local input parameters and costs from 2013.

Results Vaccinating 30% of the Spanish population aged 50 years and older resulted in €16,577/QALY gained, €2025/HZ case avoided, and €5594/PHN case avoided under the third-party payer perspective. From a societal perspective, the ICERs increased by 6%, due to the higher price of the vaccine. The number needed to vaccinate to prevent one case was 20 for HZ, and 63 for PHN3. Sensitivity analyses showed that the model was most sensitive to the HZ and PHN epidemiological data, the health state utilities values, and vaccine price used.

Conclusion Considering an acceptable range of cost-effectiveness of €30,000–€50,000 per QALY gained, vaccination of the 50+ population in Spain against HZ with a new vaccine, Zostavax, is cost-effective and makes good use of the valuable healthcare budget.     

Lancaster's characteristics approach revisited: product selection using non‐parametric methods

In consumer theory, the principles of Lancaster's characteristics approach and hedonic pricing appear to offer the most promising insight into choice when qualitative aspects are important. The paper reconciles these principles with the family of non‐parametric frontier estimation methods known as data envelopment analysis. It is shown that, with some straightforward adjustments, DEA is entirely consistent with the characteristics view of consumer choice found in the economics literature. In making Lancaster's ideas operational, the paper also addresses the theoretical concern voiced by Lancaster about combining indivisible products. The principles are illustrated with a case study involving the comparison of diesel cars. The paper concludes that the user will ultimately have to apply some judgement in choosing between competing efficient products. However, the analysis should help to restrict the number of products to be assessed to manageable proportions. Copyright © 2002 John Wiley & Sons, Ltd.     

A simulation-based algorithm for American executive stock option valuation

We present an algorithm that merges a certainty-equivalence framework with the least-squares Monte Carlo algorithm to obtain the executive stock option (ESO) value for a risk-averse and undiversified agent. We account for the difference between executive’s value and firm cost of the ESO. We show how early-exercise decisions depend on executive’s preferences and its diversification degree. Because of the algorithm flexibility, it allows for multiple state-variables. As an example, we consider the case of indexed ESOs revealing a significant improvement in terms of executive’s discount respect to fixed strike ESOs.     

Conceptualising ‘shadow landscape’ in political ecology and rural studies

This paper develops the concept of ‘shadow landscape’ in order to describe the essential otherness and seemingly distinctive if ever contingent properties of in-between rural places characterised by historical depopulation and cultural marginalisation. It does so first of all through a critically sympathetic assessment of how these areas have been portrayed in the fields of political ecology and rural studies. In political ecology, reference has long been made to ‘depopulated areas’ whereas in rural studies there has been recently talk of ‘marginal cultures’. The result tends to be a ‘pre-given socio-spatial container’ (Zimmerer and Bassett, 2003) that often obscures more than it reveals about these distinctive locations. The paper thereafter outlines the concept of shadow landscape as a means by which to understand these areas, and does so via a discussion of marginality, scale, socio-nature and ‘cultures of depopulation’. In the process, some of the key material and discursive issues that surround these ‘imagined communities’ are brought into focus. The conclusion considers a future research agenda based on an understanding shaped by the concept of shadow landscape.     

Adaptation of Agroforestry Systems in South-Eastern Mexico through Integration of Farmer and Bioeconomic Evaluations

Agroforestry systems have been promoted as sustainable land-use systems for regions where shifting agriculture is the traditional predominant land-use. Although environmentally sustainable, agroforestry systems require investment to establish that may affect their economic sustainability. In the southern Yucatan Peninsula 47 agroforestry plots of two timber and 10 fruit tree species were established with 22 farmers in three communities covering two rainfall zones and five soil types. Some fruit trees had wide adaptability to different soil, rainfall and management conditions, e.g. Manilkara zapota; others were restricted to the best soil, rainfall management conditions, e.g. Persea americana. The Meliaceae timber trees responded little to rainfall and soil, but stem borer attack was markedly lower in less intensively managed systems. Level of system maintenance greatly affected costs, but also opportunities for intercropping and obtaining immediate income. All levels of managements had negative net present value (NPV) for the three-year establishment phase, but so does traditional maize production. Farmers preferred to inter-crop their agroforestry systems, but were often limited by site quality. Determining sustainable agroforestry options for farmers requires multiple decisions related to species adaptability to the site, farmer production objectives and farmer capacity to invest in different management strategies. One production technology did not fit all.     

The rural as a site of recreation: evidence and contradictions in Spain from a geographical perspective

There is a wide range of individual or collective interpretations of the conceptualisation of rurality. Rural tourism (RT) is a key component in the politics of rural spaces in Europe and, consequently, is clearly associated with the debate about rurality in each country. In addition to RT, this paper studies the framework of commoditisation, associated with its distinct character in each situation, depending on the actors involved in each process, policy or manifestation. It also discusses the role of tourism in generating different notions of rurality among the Spanish regional authorities. The information source used here consists in the critical analysis of national and regional regulations and the policy documents on RT since 1960. The paper finally concludes that RT is an important factor in the generation of different perspectives of rurality in Spain, which corresponds to its main role, rather than its socioeconomic effects, which have been limited to counteracting the effects of the rural exodus.     

On Export Composition and Growth

The hypothesis that exports in technology-intensive industries have a higher potential for positive externalities coupled with higher productivity levels (due to higher rates of capitalization) is tested using a comprehensive and detailed data set, covering 45 industrialized and developing countries and including exports of 33 industries over the time period 1981–1997. The estimation results, using a random effects model and employing an instrumental variables estimator, support the hypothesis of qualitative differences between high- and low-tech exports with respect to output growth. The superior performance of high-tech exports stems from their positive productivity differential to the domestic sector, while the externality effect is not significant at any meaningful level of significance. The positive productivity differential is only significant for the subsample of developing countries. No significant effects were found to be present in the subsample of OECD member countries. JEL no. O41, O50, C23, F14