Stochastic analysis in life office management: applications to large annuity portfolios

The paper deals with the riskiness analysis for a large portfolio of life annuities. By means of the limiting distribution of the present value of the portfolio, in the first part of the paper a model for evaluating the investment and the projection risks is presented. In the second part, with regard to the investment risk's effects, the insolvency risk is measured considering the cumulative probability distribution function of the discounted average cost per policy. Copyright © 2003 John Wiley & Sons, Ltd.     

Multiple factor analysis in environmental chemistry

In environmental chemistry studies, it may be necessary to analyze data sets constituted by different blocks of variables, possibly of different types, measured on the same samples. Multiple factor analysis (MFA) is presented as a tool for exploring such data. The most important features of MFA are shown on a real environmental data set, consisting of two blocks of data, namely heavy metals and polycyclic aromatic hydrocarbons, measured for sediment samples. They are discussed and compared to principal component analysis (PCA). The usefulness of the weighting scheme used in MFA as a preprocessing step for other chemometric methods, such as clustering, is also highlighted.     

惯例复制与知识转移:作用机制的权变条件研究

针对惯例复制过程中与外部情景难以匹配的复制困境,分析了常规惯例复制和柔性惯例复制对知识转移的单独以及联合作用的关系悖论,对比分析作用机制在网络闭合性和环境不确定性约束下的权变性影响。以研发密集型企业为对象,运用多元回归分析进行实证检验。结果表明:网络闭合性和环境不确定性是惯例复制对知识转移的单独以及联合作用的权变条件;网络闭合性强化了常规惯例复制机制的促进作用,但限制了柔性惯例复制机制的效能发挥;环境不确定性削弱了常规惯例复制机制的促进作用,对柔性惯例复制机制的作用效果不显著;网络闭合性低或环境不确定性低时,两种惯例复制机制的联合作用相互补充,而网络闭合性高或环境不确定性高时,两种惯例复制机制相互替代。研究结论有助于揭示惯例复制的权变作用,对提升技术创新网络的知识转移效率具有重要意义。     

Central limit theorem for quadratic forms for sparse tables

Sufficient conditions for asymptotic normality for quadratic forms in {n_t − np_t} are given, where {n_t} are the observed counts with expected cell means {np_t}. The main result is used to derive asymptotic distributions of many statistics including the Pearson's chi-square.     

On the Padé table for e x and the simple continued fractions for e and e L/M

A recently observed connection between some Padé approximants for the exponential series and the convergents of the simple continued fraction for e is established, leading to an alternative proof of the latter. Similar results for the simple continued fraction e ²,e ^1/M and e ^2/M , when M is a natural number greater than one, are derived.      

The crystal and molecular structure of cyclopentadienyltin(II) chloride. The bonding of the cyclopentadienyl group in tin(II) compounds

The crystal and molecular structure of cyclopentadienyltin(II) chloride has been determined from three-dimensional X-ray data. The crystals are orthorhombic, space group Pc2₁n. The unit cell, of dimensions a = 5.711(5), b = 6.225(5), c = 17.24(2) Å, contains four molecules. The structure has been refined by full matrix least squares techniques to a final R value of 0.083 for 717 independent reflections. In the crystal unsymmetrical tin-chlorine bridges are present between the units of C₅H₅SnCl.It is suggested that in cyclopentadienyltin(II) compounds the cyclopentadienyl group occupies more than one coordination site as a result of the donation of π electron density from the cyclopentadienyl ring into an empty acceptor orbital of the tin atom having π symmetry.     

Modelling and forecasting mortality in Spain

Experience shows that static life tables overestimate death probabilities. As a consequence of this overestimation the premiums for annuities, pensions and life insurance are not what they actually should be, with negative effects for insurance companies or policy-holders. The reason for this overestimation is that static life tables, through being computed for a specific period of time, cannot take into account the decreasing mortality trend over time. Dynamic life tables overcome this problem by incorporating the influence of the calendar when graduating mortality. Recent papers on the topic look for the development of new methods to deal with this dynamism.     

The AME 2020 atomic mass evaluation (I). Evaluation of input data,and adjustment procedures

This is the first of two articles(Part I and Part II)that presents the results of the new atomic mass evaluation,Ame2020.It includes complete information on the experimental input data that were used to derive the tables of recommended values which are given in Part II.This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction,decay and mass-spectrometric data which were used in a least-squares fit adjustment in order to determine the recommended mass values and their uncertainties.All input data,including both the accepted and rejected ones,are tabulated and compared with the adjusted values obtained from the least-squares fit analysis.Differences with the previous Ame2016 evaluation are discussed and specific examples are presented for several nuclides that may be of interest to Ame users.     

The valuation of life contingencies: A symmetrical triangular fuzzy approximation

This paper extends the framework for the valuation of life insurance policies and annuities by Andrés-Sánchez and González-Vila (2012, 2014) in two ways. First we allow various uncertain magnitudes to be estimated by means of fuzzy numbers. This applies not only to interest rates but also to the amounts to be paid out by the insurance company. Second, the use of symmetrical triangular fuzzy numbers allows us to obtain expressions for the pricing of life contingencies and their variability that are closely linked to standard financial and actuarial mathematics. Moreover, they are relatively straightforward to compute and understand from a standard actuarial point of view.     

Toric statistical models: parametric and binomial representations

Toric models have been recently introduced in the analysis of statistical models for categorical data. The main improvement with respect to classical log-linear models is shown to be a simple representation of structural zeros. In this paper we analyze the geometry of toric models, showing that a toric model is the disjoint union of a number of log-linear models. Moreover, we discuss the connections between the parametric and algebraic representations. The notion of Hilbert basis of a lattice is proved to allow a special representation among all possible parametrizations.