Recommender Systems with Characterized Social Regularization

Social recommendation, which utilizes social relations to enhance recommender systems, has been gaining increasing attention recently with the rapid development of online social network. Existing social recommendation methods are based on the fact that users preference or decision is influenced by their social friends' behaviors. However, they assume that the influences of social relation are always the same, which violates the fact that users are likely to share preference on diverse products with different friends. In this paper, we present a novel CSR (short for Characterized Social Regularization) model by designing a universal regularization term for modeling variable social influence. Our proposed model can be applied to both explicit and implicit iteration. Extensive experiments on a real-world dataset demonstrate that CSR significantly outperforms state-of-the-art social recommendation methods.Comment: to appear in CIKM 201

長寿社会における高齢者のアクティブエイジングとその支援 : 総合型地域スポーツクラブを対象として

早大学位記番号:新6522早稲田大

Economic analysis of medical malpractice claims and costs in Taiwan

Thesis (Ph.D.)--Boston UniversityThe number of medical malpractice claims has been increasing in recent years. However, because of the sensitiveness of information and no malpractice insurance coverage, no objective claims-based data has been released in Taiwan to estimate malpractice risk and its economic burden. In a university hospital of Taiwan, after forming a working group for solving malpractice claims in the past 6 years (2005-2010), we have collected 445 cases and examined the clinical, administrative, economic and legal information for these cases. First, after applying the Theory of Planned Behavior as our conceptual framework, we have performed several risk-adjustment models of associated factors on the odds of having legal action. Our main results are that the number of meetings between doctor and patient (OR= 2.478, p less than O.OOO1), along with other factors are significantly associated with the incidence of a malpractice claim developing into a legal action (c-statistics= 0.838). Second, using the amount of compensation as the outcome variable in all settled claims, we have constructed two-part models to describe the relationship between risk factors and outcome. The two-part models contain a logistic regression model as the first part to predict the frequency of paid claims (4.2 times more odds of having paid claims with every meeting between doctor and patient, OR= 4.235, p<0.001; c-statistics= 0.918) and an ordinary linear regression model as the second part to predict the amounts of these payments (every meeting between doctors and patient increasing the payment at 0.18 million NTD [R-square= 0.5521]). Our third study estimates nationwide malpractice costs for Taiwan based on our database, given limitations of extrapolating from a single hospital. We find that the estimated annual cost of medical malpractice for all of Taiwan's doctors is NTD 239.6 million (7.99 million USD) with a range from NTD 168.6 million to 404.3 million (5.62 million to 13.4 million USD). Such a low estimate may be caused by low lawsuit costs (42.7 million NTD, 1.42 million USD) and lower paid claims ratio for settled claims (21%). The results of the legal-economic analysis will contribute to forming a rational basis for policy debate for current malpractice reform in Taiwan

The protection of property rights through compensation -- observations from Taiwan

Literature suggests three compensation principles for property expropriation ­ full, lump sum and market value. While it is difficult to judge which principle is superior, there is no doubt that everyone should be treated equally. Owners of property in Taiwan are required through valuation practices rather than by legislation to give up part of their property value in the public interest. Compensation to the expropriated property owners is collectively paid by the citizens, usually through taxation, and all property owners are equally liable to lose property. The tradeoff between tax burden and excessive sacrifice finds a balance at market value. Taiwan applies the same valuation methodology to both property taxation assessment and expropriation compensation. The taxbased value has proved to be significantly below the market value. However, the gap between the assessed and market value is narrowed by a deliberate increase in the announced current land value shortly before expropriation. This article presents a comparison of market value and compensation amount for a set of sample properties in Taiwan on the assumption that they were to be expropriated. Its main finding is that the gap between the two is not uniform among properties. That is to say, under the present ad hoc valuation rule, some properties tend to be overcompensated while some others are undercompensated relative to market value. The empirical analysis has uncovered two valuation issues related to compensation in Taiwan that warrant further investigation: (i) whether the ad hoc valuation rules plus the flexible additional compensation satisfactorily reflect the market value; and (ii) whether the difference between market value and the amount of compensation determined remains uniform among properties