Ruin models with investment income

This survey treats the problem of ruin in a risk model when assets earn investment income. In addition to a general presentation of the problem, topics covered are a presentation of the relevant integro-differential equations, exact and numerical solutions, asymptotic results, bounds on the ruin probability and also the possibility of minimizing the ruin probability by investment and possibly reinsurance control. The main emphasis is on continuous time models, but discrete time models are also covered. A fairly extensive list of references is provided, particularly of papers published after 1998. For more references to papers published before that, the reader can consult [47].Comment: Published in at http://dx.doi.org/10.1214/08-PS134 the Probability Surveys (http://www.i-journals.org/ps/) by the Institute of Mathematical Statistics (http://www.imstat.org

Building simulated queries for known-item topics: an analysis using six european languages

There has been increased interest in the use of simulated queries for evaluation and estimation purposes in Information Retrieval. However, there are still many unaddressed issues regarding their usage and impact on evaluation because their quality, in terms of retrieval performance, is unlike real queries. In this paper, we focus on methods for building simulated known-item topics and explore their quality against real known-item topics. Using existing generation models as our starting point, we explore factors which may influence the generation of the known-item topic. Informed by this detailed analysis (on six European languages) we propose a model with improved document and term selection properties, showing that simulated known-item topics can be generated that are comparable to real known-item topics. This is a significant step towards validating the potential usefulness of simulated queries: for evaluation purposes, and because building models of querying behavior provides a deeper insight into the querying process so that better retrieval mechanisms can be developed to support the user

Are Risk Aversion and Impatience Related to Cognitive Ability?

This paper investigates whether risk aversion and impatience are correlated with cognitive ability. We conduct incentive compatible choice experiments measuring risk aversion, and impatience over an annual time horizon, for a representative sample of roughly 1,000 German adults. A measure of cognitive ability is provided by two submodules of one of the most widely used IQ tests. Interviews are conducted in subjects'' own homes. We find that lower cognitive ability is associated with greater risk aversion, and more pronounced impatience. These relationships are statistically and economically significant, and robust to controlling for personal characteristics, educational attainment, income, and measures of liquidity constraints. We perform a series of additional robustness checks, which help rule out other possible confounds.Economics ;

An inventory control project in a major Danish company using compound renewal demand models

We describe the development of a framework to compute the optimal inventory policy for a large spare-parts’ distribution centre operation in the RA division of the Danfoss Group in Denmark. The RA division distributes spare parts worldwide for cooling and A/C systems. The warehouse logistics operation is highly automated. However, the procedures for estimating demands and the policies for the inventory control system that were in use at the beginning of the project did not fully match the sophisticated technological standard of the physical system. During the initial phase of the project development we focused on the fitting of suitable demand distributions for spare parts and on the estimation of demand parameters. Demand distributions were chosen from a class of compound renewal distributions. In the next phase, we designed models and algorithmic procedures for determining suitable inventory control variables based on the fitted demand distributions and a service level requirement stated in terms of an order fill rate. Finally, we validated the results of our models against the procedures that had been in use in the company. It was concluded that the new procedures were considerably more consistent with the actual demand processes and with the stated objectives for the distribution centre. We also initiated the implementation and integration of the new procedures into the company’s inventory management systemBase-stock policy; compound distribution; fill rate; inventory control; logistics; stochastic processes

Are Risk Aversion and Impatience Related to Cognitive Ability?

Th is paper investigates whether risk aversion and impatience are correlated withcognitive ability. We conduct incentive compatible choice experiments measuringrisk aversion, and impatience over an annual time horizon, for a representative sampleof roughly 1,000 German adults. A measure of cognitive ability is provided by twosubmodules of one of the most widely used IQ tests. Interviews are conducted insubjects’ own homes. We fi nd that lower cognitive ability is associated with greaterrisk aversion, and more pronounced impatience. Th e relationships are statisticallyand economically signifi cant, and robust to controlling for personal characteristics,educational attainment, income, and measures of liquidity constraints. We perform aseries of additional robustness checks, which help rule out other possible confounds.(JEL codes: C93, D01, D80, D90, J24, J62).education, training and the labour market;