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).     

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.     

Country spreads and emerging countries: Who drives whom?

This paper attempts to disentangle the intricate relation linking the world interest rate, country spreads, and emerging-market fundamentals. It does so by using a methodology that combines empirical and theoretical elements. The main findings are: (1) US interest rate shocks explain about 20% of movements in aggregate activity in emerging economies. (2) Country spread shocks explain about 12% of business cycles in emerging economies. (3) In response to an increase in US interest rates, country spreads first fall and then display a large, delayed overshooting; (4) US-interest-rate shocks affect domestic variables mostly through their effects on country spreads; (5) The feedback from emerging-market fundamentals to country spreads significantly exacerbates business-cycle fluctuations.     

上海高龄体弱老人家庭亲属照顾者的生活满意度:照顾资源的作用

对上海城区697对75岁及以上的体弱老人及其家庭亲属照顾者作了抽样调查和统计分析。家庭亲属照顾者的照顾资源是影响高龄体弱老人生活满意度的显著因素。经济资源充分、家庭和朋友支持充足、健康自评相对好、运用积极应对策略的照顾者有较高的生活满意度。要提升家庭亲属照顾者的心理健康,首要的任务之-是增强照顾资源,包括经济的、健康的、心理的、社会的资源。     

Does indigenous and campesino traditional agriculture have anything to contribute to food sovereignty in Latin America? Evidence from Chile,Peru, Ecuador,Colombia, Guatemala and Mexico

The current challenge for world agriculture is to provide food for a growing population, within a context of environmental degradation and economic inequality. The challenge is how to produce accessible, healthy, diverse, nutritious, safe and abundant food in a way that is sustainable, allowing farmers to exert food sovereignty while at the same time addressing ecosystem conservation. The aim of this study is to explore the potential contribution of traditional agriculture to food sovereignty and also to understand the challenges that indigenous communities are facing today. Our case studies are from six Latin-American countries: Chile, Peru, Ecuador, Colombia, Guatemala and Mexico, where we carried out semi-structured, guided visits and field observations. Our results shed light on how traditional agricultural knowledge, techniques and practices can contribute to these issues, but also to the need of protecting and recovering the cultural and ecological heritage. There is a need to resolve public management issues, related to development investment, technological packages, cultural loss and gender. If these are not addressed, the potential contribution of ancient agricultural knowledge will fail to contribute to strengthen food sovereignty and maintain the local markets, which are also places for seed exchange, knowledge sharing and social networking.     

Volatility of volatility is (also) rough

Using high-frequency data for major volatility indexes, we compute the volatility of volatility and show that its logarithm follows a fractional Brownian motion with Hurst parameter smaller than 1/2 thereby extending to the volatility asset class the recent findings obtained for the equity index markets. The results confirm that the volatility of volatility is a rough process and it possesses the long memory property. We also show that the correlation between the volatility and the volatility of volatility is positive, consistent with observations in the volatility option market. Lastly, a robustness check using volatility futures confirms the findings.