Capacity constraints and the dynamics of underwriting profits

The presence of an underwriting profit cycle in property/liability insurance has become a stylized fact. Models of this'underwriting cycle'imply that the insurance market is governed by two regimes, as capacity is constrained or not. We apply the smooth transition regression model to insurance industry data for 1934–1993 to test for a regime shift. We find a rapid shift between two distinct regimes with different dynamics. When capacity is not restricted, we find no evidence of a cycle. The cycle is present in periods when capacity is restricted, immediately following World War II and after 1968. The underwriting cycle appears to be a recent phenomenon.     

Multilevel IRT models for the university teaching evaluation

In this paper, a generalization of the two-parameter partial credit model (2PL-PCM) and of two special cases, the partial credit model (PCM) and the rating scale model (RSM), with a hierarchical data structure will be presented. Having shown how 2PL-PCM, as with other item response theory (IRT) models, may be read in terms of a generalized linear mixed model (GLMM) with two aggregation levels, a presentation will be given of an extension to the case of measuring the latent trait of individuals aggregated in groups. The use of this Multilevel IRT model will be illustrated via reference to the evaluation of university teaching by students following the courses. The aim is to generate a ranking of teaching on the basis of student satisfaction, so as to give teachers, and those responsible for organizing study courses, a background of information that takes the opinions of the direct target group for university teaching (that is, the students) into account, in the context of improving the teaching courses available.     

Modernization and Tradition in the Recent History of Italian Fertility

The secular decline of Italian fertility, started in the last decade of the nineteenth century, came to an end in the early 1950'sand has recovered slightly in the last fifteen years. Italian experience seems to follow, with a twenty-year lag, the experience of the more advanced western European populations. At present, with an average of 2.5 children per marriage, Italian fertility is very close to the French and to the average European level.At the regional level, two contrasting patterns can be detected. On one side stands the very low fertility of the North and of the Center, mostly below replacement in the last thirty years;on the other, the still high fertility of the South.In the North and in the Center, where the decline started earlier, fertility has fallen well below replacement level in the last thirty years. In the South, where the decline started in the late 1920's and early 1930's, a large family system still prevails, and the spreading of voluntary control faces barriers setup by a long historyof cultural isolation,attachment to tradition and religion. In the last 15 years, however, the gap has narrowed slowly, more because of an upturn of fertility in the North and in the Center than because of the decline in the South.Another interesting feature of Italian fertility is low class differentials: the fertility of the most prolific segment (farmers, farm laborers) is only 20 percent higher than the fertility of the less prolific professional groups. Finally, Italian experience provides an interesting example of the changing relationship linking the economic level of the population and fertility changes; in 1931-51 a negative correlation linked the changes in fertility to the economic level of the region, while in 1951-61 and 1961-66 a very high and positive correlation can be observed.As for the future trends in fertility, two factors may have an important role. In the first place, on the one hand, the economic policy of the government, aiming at reducing the economic gap between the South and the rest of the country, may accelerate the leveling of regional fertility differentials. The same effect, on the other hand, may be reached by more liberal legislation, now under way, for birth control and family planning propaganda.     

The effects of smoking laws on seating allocations of restaurants, bars, and taverns

Supporters of smoking laws often argue that they do not harm restaurants, bars, and taverns and may even raise their profits. Opponents argue that owners cater to customer preferences regarding smoking and that laws mandating specific smoking policies will therefore negatively impact profits of some firms. This article tests hypotheses regarding how smoking laws affect seating allocations, using data from a nationwide survey of restaurant and bar owners. The empirical evidence indicates that smoking laws exert no significant effect on seating allocations. Firms are shown to allocate greater shares of seating to nonsmoking use when customers exhibit stronger preferences for such seating.     

Fertility and nuptiality changes in Spain from the late 18th to the early 20th century

Abstract 3.1. A regional approach often reveals features of population trends not evident in national data. We have already pointed out that the 1768 census followed the ecclesiastical sub-divisions of the country; therefore its territorial data are not comparable with those derived from later enumerations. The 1787 and 1797 censuses, on the other hand, were based on civil sub-divisions, which can be compared, when aggregated, with later censuses of the modern statistical era.     

自动往返电动小汽车的设计原理与制作方法

本文介绍了采用脉冲主动采集、计数程序控制、虚拟脉冲复位、撞击转向的方式完成自动往返电动小汽车的构思、设计及制作的方法。     

A Class of Multidimensional Latent Class IRT Models for Ordinal Polytomous Item Responses

We propose a class of multidimensional Item Response Theory models for polytomously-scored items with ordinal response categories. This class extends an existing class of multidimensional models for dichotomously-scored items in which the latent abilities are represented by a random vector assumed to have a discrete distribution, with support points corresponding to different latent classes in the population. In the proposed approach, we allow for different parameterizations for the conditional distribution of the response variables given the latent traits, which depend on the type of link function and the constraints imposed on the item parameters. Moreover, we suggest a strategy for model selection that is based on a series of steps consisting of selecting specific features, such as the dimension of the model (number of latent traits), the number of latent classes, and the specific parameterization. In order to illustrate the proposed approach, we analyze a dataset from a study on anxiety and depression on a sample of oncological patients.     

Use of a case study in sequencing/scheduling research

This paper describes a study of an industrial sequencing/scheduling problem. The study contains the definition of the problem, data requirements and examination of solution technique. Definition of the problem is discussed from the aspect of uniqueness of the specific system. Discussion of data requirements includes availability and accuracy, while examination of solution technique considers limitation of time, computer capacity, etc., as well as the possibility of imbedding available algorithms into the solution procedure. Conclusions are presented relative to the use of the case study approach in sequencing/scheduling research.