A Non-parametric Frailty Model for Temporally Clustered Multivariate Failure Times

Abstract A model is introduced here for multivariate failure time data arising from heterogenous populations. In particular, we consider a situation in which the failure times of individual subjects are often temporally clustered, so that many failures occur during a relatively short age interval. The clustering is modelled by assuming that the subjects can be divided into ‘internally homogenous’ latent classes, each such class being then described by a time‐dependent frailty profile function. As an example, we reanalysed the dental caries data presented earlier in Härkänen et al. [Scand. J. Statist. 27 (2000) 577], as it turned out that our earlier model could not adequately describe the observed clustering.     

On the difficulty of making social choices

The difficulty of making social choices seems to take on two forms: one that is related to both preferences and the method used in aggregating them and one which is related to the preferences only. In the former type the difficulty has to do with the discrepancies of outcomes resulting from various preference aggregation methods and the computation of winners in elections. Some approaches and results which take their motivation from the computability theory are discussed. The latter institution-free type of difficulty pertains to solution theory of the voting games. We discuss the relationships between various solution concepts, e.g. uncovered set, Banks set, Copeland winners. Finally rough sets are utilized in an effort to measure the difficulty of making social choices.     

Mixed estimation of old-age mortality

"Section 2 will first extend the method of mixed estimation to maximum likelihood estimation in general. Then, we will review generalized linear models with logistic and Poisson regressions as examples. In Section 3 we discuss different approaches for formulating the auxiliary information in practice. Section 4 first reviews the method of Coale and Kisker, provides empirical estimates for it, and then proceeds with the mixed estimation variant. In Section 5 we apply the methods to the estimation of mortality at ages 80+ in Finland in 1980-1993. We will first consider the evidence for mortality crossover between males and females....Then we will estimate life expectancies at age 100." (EXCERPT)     

Scenarios,uncertainty and conditional forecasts of the world population

This study is concerned with the methods available for the forecasting of future trends in the world's population. Particular attention is given to the problem of the uncertainties that these forecasts include. "The purpose of this paper is to show how subjective and data-based probabilistic assessments of error can be combined, to give a user a realistic assessment of the uncertainty of demographic forecasts, and to apply these concepts to forecasts of the world population. Moreover, we shall show how conditional forecasts can provide a simple conceptual framework in which to view scenarios. They can be particularly useful in the evaluation of proposed policies. Indeed, the so-called environmental impact assessments...that are now mandatory in many countries for major construction projects typically contain elements of conditional forecasting." The concepts discussed are illustrated by comparing a scenario of future global population growth prepared at the Institute of Applied Systems Analysis with a UN population projection.     

Invariant co-ordinate selection

Summary.  A general method for exploring multivariate data by comparing different estimates of multivariate scatter is presented. The method is based on the eigenvalue–eigenvector decomposition of one scatter matrix relative to another. In particular, it is shown that the eigenvectors can be used to generate an affine invariant co-ordinate system for the multivariate data. Consequently, we view this method as a method for invariant co-ordinate selection . By plotting the data with respect to this new invariant co-ordinate system, various data structures can be revealed. For example, under certain independent components models, it is shown that the invariant co- ordinates correspond to the independent components. Another example pertains to mixtures of elliptical distributions. In this case, it is shown that a subset of the invariant co-ordinates corresponds to Fisher's linear discriminant subspace, even though the class identifications of the data points are unknown. Some illustrative examples are given.     

Effect of aggregation on the estimation of trend in mortality

There are three approaches to analyzing and forecasting age‐specific mortality: (1) analyze age‐specific data directly, (2) analyze each cause‐specific mortality series separately and add the results, (3) analyze cause‐specific mortality series jointly and add the results. We show that if linear models are used for cause‐specific mortality, then the three approaches often give close results even when cause‐specific series are correlated. This result holds for cross‐correlations arising from random misclassification of deaths by cause, and also for certain patterns of systematic misclassification. It need not hold, if one or more causes serve as “leading indicators”; for the remaining causes, or if outside information is incorporated into forecasting either through expert judgment or formal statistical modeling. Under highly nonlinear models or in the presence of modeling error the result may also fail. The results are illustrated with U.S. age‐specific mortality data from 1968–1985. In some cases the aggregate forecasts appear to be the more credible ones.     

Moral Regulation: A Reformulation

Philip Corrigan and Derek Sayer introduced the concept of moral regulation to contemporary sociological debate in their historical sociology of English State formation, The Great Arch (1985). In their work they fuse Durkheimian and Foucauldian analysis with a basic Marxist theory. However, this framework gives too limited a perspective to their analysis. I suggest that moral regulation should not be seen as a monolithic project, as merely action by and for the State, nor as activity by the ruling elite only. It should be seen as a form of social control based on changing the identity of the regulated. Its object is what Weber calls Lebensführung , which refers to both the ethos and the action constituting a way of life. The means of moral regulation are persuasion, education, and enlightenment, which distinguishes it from other forms of social control. Analyzing the social relations of moral regulation provides a useful perspective on this form of social action.     

On continuity of Arrovian social welfare functions

We study continuity properties of Arrovian social welfare functions in the infinite population framework. We show that continuous welfare functions satisfying unanimity and independence of irrelevant alternatives are dictatorial. Weak anonymity is shown to be incompatible with continuity and unanimity: every continuous weakly anonymous social welfare function must be a constant function.     

Entrepreneurs and producers: Identities of Finnish farmers in 2001 and 2006

The farmers' role within the EU has recently been under reconstruction: in addition to primary agricultural production farmers should fulfil multiple functions such as maintaining the rural landscape, conserving nature and providing services. One essential feature of this new role is the demand for entrepreneurship. Farmers should be capable of competing in the worldwide, global agricultural market. They are also encouraged to diversify into business activities beyond agriculture. How do farmers see themselves in this situation? Is their self-perception compatible with this new reconstruction of the farming economy and the farmers' role? Research, thus far, seems to indicate that traditional or production oriented identities are still dominant among farmers. But there is also some evidence that new identities, such as the entrepreneurial identity, are emerging. In our study we are especially interested in how Finnish farmers have met the demand for adapting to the role of an entrepreneur. We approach the issue of the farmers' changing role from a social psychological perspective by utilizing the concept of identity. Our empirical evidence comes from two nation-wide postal questionnaire data sets, both containing samples from three subgroups: conventional farmers focusing solely on primary agricultural production, diversified farmers who also had other business besides agricultural production, and rural non-agricultural small-scale businesses. The results show that Finnish farmers do not experience “entrepreneur” as something distant from themselves and as not fitting in with their world of ideas, as the work of some researchers would depict. Instead, the majority of Finnish farmers, especially diversified farmers, conceive of themselves both as entrepreneurs and as producers.     

Relating Changes in Life Expectancy to Changes in Mortality

I address the problem of what can be said of changes in mortality rates, if one knows how life expectancies change. I note a general formula relating life expectancies in different ages to mortality and prove that if mortality changes over time following a proportional-hazard model, then there is a one-to-one correspondence between life expectancy at birth and mortality rates. Extensions and an application of these results to the analysis of mortality change are presented.