Model misspecification,Bayesian versus credibility estimation,and Gibbs posteriors

ABSTRACT

In the context of predicting future claims, a fully Bayesian analysis – one that specifies a statistical model, prior distribution, and updates using Bayes's formula – is often viewed as the gold-standard, while Bühlmann's credibility estimator serves as a simple approximation. But those desirable properties that give the Bayesian solution its elevated status depend critically on the posited model being correctly specified. Here we investigate the asymptotic behavior of Bayesian posterior distributions under a misspecified model, and our conclusion is that misspecification bias generally has damaging effects that can lead to inaccurate inference and prediction. The credibility estimator, on the other hand, is not sensitive at all to model misspecification, giving it an advantage over the Bayesian solution in those practically relevant cases where the model is uncertain. This begs the question: does robustness to model misspecification require that we abandon uncertainty quantification based on a posterior distribution? Our answer to this question is No, and we offer an alternative Gibbs posterior construction. Furthermore, we argue that this Gibbs perspective provides a new characterization of Bühlmann's credibility estimator.     

市政给排水施工中顶管技术的应用分析

管道主要起到排放城市给排水作用,是市政道路工程的重要组成部分.给排水管道施工效果对市政道路的运行具有直接影响.顶管技术是一项有效的施工技术,在给排水管道施工中应用的也较为广泛,可满足给排水管道施工要求.为进一步提高顶管技术在给排水管道中施工效果,还需以工程实例为主要研究对象,科学、合理地选择和运用顶管技术,保证市政给排水管道施工质量.     

Reassessing measures of sustainable firm performance: A consultant's guide to identifying hidden costs in corporate disclosures

Strategy, management, corporate social responsibility, critical accounting, and other business researchers frequently utilize financial metrics such as return on assets, return on equity, and return on sales as proxy measures for the financial performance of firms. Large data sets offer convenience but exclude the textual data of corporate disclosures that offers critical insight into specific executive actions and social and environmental outcomes. This study looks at the detrimental consequences of the prevalent practice of relying on macrofinancial metrics as measures of firm performance. Insight from the socioeconomic approach to management (SEAM) is then applied to help an external analyst develop the perspective of an internal consultant to identify hidden costs in corporate disclosures. An extensive case on former CEO Robert Nardelli's tenure at Home Depot is presented as an example of applied SEAM theory to explore how a causal network of dysfunctions can be traced through publicly available financial disclosures. The management discussion and analysis as well as the executive incentive compensation formulas serve as a roadmap to discover hidden costs. The study offers a critical perspective of financial disclosures to allow researchers to externally diagnose dysfunctions sooner rather than years later, an insight formerly only available to internal consultants.     

Weighted utility optimization of the participating endowment contract

ABSTRACT

In a participating endowment contract, the special loss compensation and profit sharing mechanism leads to heterogeneous benchmarks to distinguish the gain and loss for the policyholder's and the insurance company's S-shaped utilities. Because of the intense competition among the insurance companies and the requirement of the regulators, the benefits of the policyholders should be considered. As such, choosing the weighted utility of the two counterparts as the optimization objective is a rational setting. This setting induces a non-HARA (hyperbolic absolute risk aversion) and non-concave objective utility whose exact concavity and convexity are unknown. The difficulties not only come from this highly non-concave optimization problem, but also exist in the implicit integration of the optimum when solving the expected utilities of the two counterparts. We originally design an identification method to establish two categories of concave envelopes to solve the optimization problem, and propose an innovative numerical integration by substitution technique to deal with the implicit integration problem. The numerical simulation results recognize the existence of Pareto improvement of the two counterparts, which shows that the utilities of the policyholder and the insurance company can be simultaneously improved by switching into the weighted objective and appropriately amending the contract.     

聚类分析在土地利用功能分区中的应用——以西安市雁塔区为例

土地利用功能分区对土地合理、集约利用以及地方经济的快速、持续的发展发挥着重要的作用,是土地利用总体规划的重要组成部分.在介绍系统聚类分析方法的基础上,以西安市雁塔区为例.在实验区内以街道办为单位,选取具有代表性的参考因子来量化分析进行土地利用功能分区.     

Wage Effects of Drinking in Australia

This article analyses the wage effects of drinking using the Australian Twin Registry data. A multinomial logit framework is employed to explain the allocation of workers across various drinking states, and to correct for selection bias in the wage equations. It is found that there is a significant positive wage premium for moderate drinking. A favourable family background (during childhood) is positively related to the measure of moderate drinking. Greater genetic endowments are also associated with moderate drinking.     

铬渣治理与综合利用

介绍了铬渣的各种无害化处理方法，即采用不同的还原方法使铬渣中的六价铬转变为无毒的三价铬，达到解毒目的。在无害化处理的基础上，阐述了对铬渣进行综合利用的途径。     

包装废弃物的处理

综合介绍了各类包装度弃物(纸类、塑料类、玻璃类、金属类及其它类)的处置处理、回收于生利用技术手段，包括减少包装量、回收复用、于生利用、焚烧发电或回收热能以及填埋等，比较了各种方法的利弊、优缺点，提出了应因地制宜，采用最适宜的方法来处理不同类别的包装废弃物，以期最大限度地使包装废弃物资源化并保护环境。     

高等院校应用型人才培养模式探讨

本文在分析国内高等教育发展现状的基础上，阐述了大众化高等教育前提下高等应用型人才的内涵及其培养模式，并结合国内经济技术发展状况及其特点，对应用型人才培养模式下课程体系的建设及规划进行了探讨。     

应该从理论上否定"原罪"概念

本文认为,民间资本、私营经济并无“原罪”。否定“原罪”概念,有三个理由。第一,马克思借用神学概念提出“原罪”,带有否定资本的意思,认为资本一出生就有罪,这不仅与其所说的资本主义生产方式在历史上起的进步作用及生产力标准相矛盾,而且从根本上否定了劳动可以进行积累,合法经营可以致富,与实际情况不符。在一个半世纪之后的今天,资本仍有活力,还能在一定范围内调整生产关系。第二,“原罪”概念是不确定的,不能成为法律用语。把利润等同于“原罪”,认为利润获得者就有“原罪”,是把“原罪”概念泛化了,使之成为一个“莫须有”的罪名。第三,“原罪”是悬在私营业主头上的一把剑,随时可能掉下来。要使民营经济、私营企业健康发展,就是要改善投资环境,落实宪法中保护私有财产的庄严规定。