Stochastic Models of Implied Volatility Surfaces

We propose a market–based approach to the modelling of implied volatility, in which the implied volatility surface is directly used as the state variable to describe the joint evolution of market prices of options and their underlying asset. We model the evolution of an implied volatility surface by representing it as a randomly fluctuating surface driven by a finite number of orthogonal random factors. Our approach is based on a Karhunen–Loeve decomposition of the daily variations of implied volatilities obtained from market data on SP500 and DAX options.
We illustrate how this approach extends and improves the accuracy of the well–known 'sticky moneyness' rule used by option traders for updating implied volatilities. Our approach gives a justification for the use of 'Vegas' for measuring volatility risk and provides a decomposition of volatility risk as a sum of independent contributions from empirically identifiable factors.
(J.E.L.: G130, C14, C31).     

Education, segregation and marital sorting: theory and an application to the UK

This paper presents a model of the intergenerational transmission of education and marital sorting. Parents matter both because of their household income and because their human capital determines the distribution of a child's disutility from making an effort to become skilled. We show that an increase in segregation has potentially ambiguous effects on the proportion of individuals that become skilled in the steady state, and hence on marital sorting, the personal and household income distribution, and welfare. We calibrate the steady state of our model to UK statistics. We find that an increase in the correlation of spouses in their years of education will bring about a small increase in the proportion of skilled individuals when the relative supply of skilled individuals is variable at the family level and a decrease when this supply is fixed. Ex-ante utility (of an unborn individual) increases in the first case and decreases in the second. The welfare effect of increased sorting is negative for unskilled individuals and positive for skilled individuals. Increased segregation always leads to an increase in welfare inequality between skilled and unskilled individuals.     

Rituals of cruise consumption and the 'new' middle class: desiring and 'devouring' maritime cruises

The consumption of maritime cruises is one of the most striking facets of the phenomenon of a new middle class emergence in Brazil. This study investigates the use of maritime cruises by emerging middle-class consumers to enact their new social status. Specifically, the research looks at ritualistic behaviour performed by consumers before, during, and after a cruise. The research uses a multi-method design characterised by a combination of ethnography and group discussions. The study contributes to enlarge McCracken’s typology of consumption rituals, showing how emerging consumers use the cruise as a rite of passage, during which they perform rituals of preparation, production, possession, and divestment. It also sheds light on specific rituals performed by consumers in order to transfer meanings from the cruise to their own selves. Finally, the findings suggest that consumption rituals in the context of social ascent may not have the transformative power of traditional rites.     

Endogenous cartel formation: Experimental evidence

In a Bertrand-oligopoly experiment, firms choose whether or not to engage in cartel-like communication and, if so, they may get fined by a cartel authority. We find that the four-firm industries form cartels more often than the duopolies because they gain less from a hysteresis effect after cartel disruption.     

Distributional effects of social security reforms: The case of France

This paper assesses the impact of two social security reforms using a calibrated, dynamic life cycle model. It quantifies the long‐run distributional impact of two sets of reforms in France: (1) the 2013 reform of Prime Minister Ayrault, which modified the parameters of a defined benefit (DB) plan, and (2) a hypothetical reform that changes the system to a notional defined contribution (NDC) plan, similar to that in Italy. First, on aggregate welfare, the Ayrault reform and the hypothetical switch to NDC yield contrasting results. The Ayrault reform improves aggregate welfare, which is not the case for the NDC reform. Welfare comparisons are made with respect to the “benchmark economy,” where increases in life expectancy occur and are dealt with only through a higher contribution rate. Second, both reforms yield unequal distributions of welfare changes, with low‐skill workers on the losing end. Under the Ayrault reform, low‐skill workers delay retirement by two years, to age 62. Under NDC reform, pensions for low‐skill workers fall substantially as inequalities during the work life translate directly into inequalities in pensions. The switch to an NDC scheme leads to a more unequal society in terms of asset and welfare distribution.     

Pedagogical and technological replanning: a successful case study on integration and transversal skills for engineering freshmen

Replanning is often used to optimize results of an activity in an ever changing world. To address the challenge of preparing future engineers for success, a special course was created for all engineering freshmen of the Faculty of Engineering of the University of Porto, in Portugal. Presented as a case study, this special course underwent a careful replanning as a result of several years of experience in teaching practice alongside with a theoretical deepening in pedagogical and technological issues, under the aegis of the action-research methodology. Within the context of the case study course, the mentioned replanning was also based on a theoretical approach that clearly identifies teaching–learning-assessment methodologies that promote regulation from those that foster emancipation, using a specific instrument: a taxonomy of educational processes. The replanning was designed to globally boost results regarding the educational aims of the course such as furthering freshmen’s integration into work environment and preparing them for success by fostering transversal skills (needed for study and work). Technology is seen as a mean of education enrichment as well as a productivity tool. The introduced innovations include fun-but-educational activities, several types of assessment over time and specific technological tools which were critical for the educational impact/achievement of this course. Success is demonstrated by encouraging feedback from the stakeholders, high students’ classifications and a steady reduction in retention. It is advocated that large portions of the reasoning behind the replanning can be extrapolated to other courses.     

Leadership Dynamics in Partially Distributed Teams: an Exploratory Study of the Effects of Configuration and Distance

Despite the importance of leadership and the wealth of empirical studies focused on leadership effectiveness in traditional and computer-supported groups, there is little research examining leadership dynamics in partially distributed virtual teams (PDTs). Virtual teams are partially distributed when they are configured with one or more subgroups of collocated members and isolated members. This paper lays the groundwork for an in-depth study of leadership in PDTs that can be extended to other types of virtual team configurations. Using three dimensions of virtual distance (geographic, cultural and temporal), we analyze how the configuration of virtual teams interacts with leadership dynamics. We also summarize the results of an exploratory study using 12 student teams to examine the effects of distance and configuration on leadership in PDTs. Findings show significant differences in leadership dynamics (i.e., leader emergence vs. leader retention) which impacted team performance. From these results, we develop propositions on leadership and PDTs.     

The productivity impact of R&D investment: are high-tech sectors still ahead?

Our aim is to investigate the relationship between a firm's R&D expenditures and its productivity, looking at sectoral peculiarities. We use a unique longitudinal database consisting of 1809 US and European manufacturing and service firms over the period 1990–2008. Our main findings can be summarised as follows. Consistently with previous literature, the knowledge stock has a significant positive impact on a firm's productivity. More interestingly, the coefficient turns out to be significantly larger in the R&D-user services and high-tech manufacturing sectors than in the non-high-tech manufacturing sectors. Contrary to the ‘latecomer advantage’ approach, these outcomes suggest that firms in high-tech sectors are still ahead in terms of impact on productivity of R&D investments.     

Quasi-structural estimation of a model of childcare choices and child cognitive ability production

This article evaluates the effects of maternal vs. alternative care providers’ time inputs on children’s cognitive development using the sample of single mothers in the National Longitudinal Survey of Youth. To deal with the selection problem created by unobserved heterogeneity of mothers and children, we develop a model of mother’s employment and childcare decisions. We then obtain approximate decision rules for employment and childcare use, and estimate these jointly with the child’s cognitive ability production function. To help identify our selection model, we take advantage of the plausibly exogenous variation in employment and childcare choices of single mothers generated by the variation in welfare rules across states and over time created by the 1996 welfare reform legislation and earlier State waivers.