Probabilistic Models for Bacterial Taxonomy

We give a survey of different partitioning methods that have been applied to bacterial taxonomy. We introduce a theoretical framework, which makes it possible to treat the various models in a unified way. The key concepts of our approach are prediction and storing of microbiological information in a Bayesian forecasting setting. We show that there is a close connection between classification and probabilistic identification and that, in fact, our approach ties these two concepts together in a coherent way.     

Causality effects in return volatility measures with random times

We provide a structural approach to identify instantaneous causality effects between durations and stock price volatility. So far, in the literature, instantaneous causality effects have either been excluded or cannot be identified separately from Granger type causality effects. By giving explicit moment conditions for observed returns over (random) duration intervals, we are able to identify an instantaneous causality effect. The documented causality effect has significant impact on inference for tick-by-tick data. We find that instantaneous volatility forecasts for, e.g., IBM stock returns must be decreased by as much as 40% when not having seen the next quote change before its (conditionally) median time. Also, instantaneous volatilities are found to be much higher than indicated by standard volatility assessment procedures using tick-by-tick data. For IBM, a naive assessment of spot volatility based on observed returns between quote changes would only account for 60% of the actual volatility. For less liquidly traded stocks at NYSE this effect is even stronger.     

股票回报率截面离差包含的信息

本文通过实证研究发现，股票回报率的截面离差包含单只股票和组合回报率未来波动的增量信息。而对非预期离差而言，当后期出现高的非预期离差时，伴随的回报率具有惯性，当后期出现低的非预期离差时，伴随的回报率呈现反转现象，这种结论无论对单个公司还是按平均市值分类的组合都是成立的。这些结论对事件研究、期权定价等需要预测价格波动的研究及更好理解价格信息都是有用的，特别在中国股市能更好理解庄家的动机。     

Intradaily volatility and adjustment

Intradaily volatility is related to the speed of adjustment of prices towards their intrinsic values. The decomposition of volatility into intrinsic and noise related components is demonstrated to be impacted by speeds of adjustment. Intradaily speeds of adjustment are estimated for U.K. index data and some empirical evidence of overreaction at the open and underreaction at the close of the trading day found for the FTSE100 index. The major result that we report in this paper is that differential intradaily volatilities at the index level are related to differential speeds of adjustment, thus providing insights into the similar results reported in U.S. index studies, such as [Gerety, M., Mulherin, J., 1994. Price formation on stock exchanges: the evolution of trading within the day. The Review of Financial Studies 7, 609–629].     

Modelling international tourism and country risk spillovers for Cyprus and Malta

Small Island Tourism Economies (SITEs) are developing sovereign countries that rely on tourism as a source of exports, and need a consistent inflow of foreign investment in order to facilitate economic growth. Access to international capital markets helps SITEs smooth out their consumption over time, while absorbing adverse domestic production shocks. This paper provides a comparison of tourism growth, country risk returns and their associated volatilities (or uncertainty) for 2 SITEs, namely Cyprus and Malta. Monthly data are available for both international tourist arrivals and composite country risk ratings compiled by the International Country Risk Guide (ICRG) for the period May 1986 to May 2002. The time-varying conditional variances of tourism growth and country risk returns for the 2 SITEs are analysed using multivariate models of conditional volatility. Empirical results show that Cyprus and Malta are complementary destinations for international tourists. Changes to tourism patterns in Cyprus lead to changes to tourism patterns in Malta. Hence, tour operators and national tourism promotion authorities in Cyprus and Malta should collaborate closely in marketing and promoting joint tourism products. Moreover, foreign entities interested in investing in the tourism sectors of Cyprus and Malta should consider investment projects that span a long period of time. The performance of the tourism sector and the associated composite risk are independent of each other for the two countries. However, there is a direct relationship between the tourism sectors of Cyprus and Malta and their respective country risk settings.     

International trade,risk taking and welfare

This paper shows that the gains from opening up to international trade are smaller when firms do not fully internalize downward risk. I develop a general equilibrium model with two key assumptions. First, when faced with adverse productivity shocks, employers can lay off workers without fully paying the social costs of their layoff decisions, a common feature of many institutions. Second, when opening to international trade, the elasticity of demand perceived by an industry increases. In this setup, I show that international trade induces firms to take more risk and (i) raises the equilibrium unemployment rate, (ii) increases the volatility of sectoral sales and (iii) increases welfare proportionately less than in the absence of the externality. Inducing firms to internalize the costs of layoff (Blanchard and Tirole, 2003) therefore appears even more important in a globalized world.     

How to make Dupire’s local volatility work with jumps

There are several (mathematical) reasons why Dupire’s formula fails in the non-diffusion setting. And yet, in practice, ad-hoc preconditioning of the option data works reasonably well. In this note, we attempt to explain why. In particular, we propose a regularization procedure of the option data so that Dupire’s local vol diffusion process recreates the correct option prices, even in manifest presence of jumps.     

Reexamining the time-varying volatility spillover effects: A Markov switching causality approach

This paper intends to examine the volatility spillover effect between selective developed markets including U.S., U.K., Germany, Japan and Hong Kong over the sample period from 1996 to 2011. We introduce a Markov switching causality method to model the potential instability of volatility spillover relationships over market tranquil or turmoil periods. This method is more flexible as no prior information on the changing points or size of sample window is needed. From the empirical results, we find the evidence of the existence of spillover effects among most markets, and the bilateral volatility spillover effects are more prominent over turmoil or crisis episodes, especially during Asia crisis and subprime mortgage crisis periods. Moreover, the distinct role of each market is also investigated.     

The determinants of hotel room rates: Another visit with Singapore's data

In this research note, volatility clustering modeling framework is used to examine the determinants of hotel room rates in Singapore. Using monthly data from January 1985 to June 2009, GARCH-M(1, 1) is identified as the appropriate model used to capture volatility clustering. The results suggest that total inbound tourists and economic performance have positive effects on hotel room rates. The main findings are (a) the occurrences of terrorist activities in the neighboring countries have negative impacts and (b) the volatility of hotel room rates has a positive effect, on hotel room rates.