ON CONVERGENCE RATES FOR NONPARAMETRIC POSTERIOR DISTRIBUTIONS

Rates of convergence of Bayesian nonparametric procedures are expressed as the maximum between two rates: one is determined via suitable measures of concentration of the prior around the “true” density f₀, and the other is related to the way the mass is spread outside a neighborhood of f₀. Here we provide a lower bound for the former in terms of the usual notion of prior concentration and in terms of an alternative definition of prior concentration. Moreover, we determine the latter for two important classes of priors: the infinite–dimensional exponential family, and the Pólya trees.     

Urban Political Theory and the Symmetrical Model of Community Power in Singapore

Modernity's concern within metropolitan regimes includes the revival of community power through 'growth machines' and 'urban regime' theory. This paper introduces the symmetrical model of community power for the creation of civil society in urban centres like Singapore which, apodictically, represents a 'First World' city-state in a 'Third World' region. Singapore's urban growth engines falls within a variety of state-sanction and quasi-private metropolitan urban regimes that have contributed to innovative uses of human and material resource allocation. But can the people creatively empower themselves? The model is premised on liberal democratic ideals of community empowerment, and represents a plausible alternative to paternalism in preparation for the uncertainties of modernity in the twenty-first century.     

An Italian pattern of social enterprise: The social cooperative

The article describes how the social cooperative has become instrumental in the expansion of the social economy in Italy. It reports the contribution these associations have made to broadening the concept and parameters of volunteer organizations, providing basic social welfare services and integrating many disadvantaged people into the active society. By virtue of their ability to activate wider social projects, this type of social enterprise could be of interest and relevance to other countries (following this example, in 2001 the French government created the Sociétés coopératives d'intérét collectif), but they call for adequate competencies and protection under specific laws because, on the whole, they are too small and depended on public contributions.     

Analysing the interevent time distribution to identify seismicity phases: a Bayesian nonparametric approach to the multiple-changepoint problem

In the study of earthquakes, several aspects of the underlying physical process, such as the time non-stationarity of the process, are not yet well understood, because we lack clear indications about its evolution in time. Taking as our point of departure the theory that the seismic process evolves in phases with different activity patterns, we have attempted to identify these phases through the variations in the interevent time probability distribution within the framework of the multiple-changepoint problem. In a nonparametric Bayesian setting, the distribution under examination has been considered a random realization from a mixture of Dirichlet processes, the parameter of which is proportional to a generalized gamma distribution. In this way we could avoid making precise assumptions about the functional form of the distribution. The number and location in time of the phases are unknown and are estimated at the same time as the interevent time distributions. We have analysed the sequence of main shocks that occurred in Irpinia, a particularly active area in southern Italy: the method consistently identifies changepoints at times when strong stress releases were recorded. The estimation problem can be solved by stochastic simulation methods based on Markov chains, the implementation of which is improved, in this case, by the good analytical properties of the Dirichlet process.     

A note on testing for nonstationarity in autoregressive processes with level dependent conditional heteroskedasticity

In this paper, we investigate the empirical distribution and the statistical properties of maximum likelihood (ML) unit-root t-statistics computed from data sampled from a first-order autoregressive (AR) process with level-dependent conditional heteroskedasticity (LDCH). This issue is of particular importance for applications on interest rate time-series. Unfortunately, the extent of the technical complexity related associated to LDCH patterns does not offer a feasible theoretical analysis, and there is no formal knowledge about the finite-sample size and power behaviour or the ML test for this context. Our analysis provides valuable guidelines for applied work and directions for future work.     

The Emergence of Lowest‐Low Fertility in Europe During the 1990s

Lowest‐low fertility, defined as a period total fertility rate at or below 1.3, has rapidly spread in Europe during the 1990s. This article traces the emergence of this new phenomenon to the interaction of five factors. First, tempo and compositional distortions reduce the total fertility rate below the associated level of cohort fertility. Second, socioeconomic changes—including increased returns to human capital and high economic uncertainty in early adulthood—have made late childbearing a rational response for individuals and couples. Third, social interaction effects reinforce this behavioral adjustment and contribute to large and persistent postponement in the mean age at birth. Fourth, institutional settings favor an overall low quantum of fertility. Fifth, postponement–quantum interactions amplify the consequences of this institutional setting when combined with ongoing delays of child‐bearing. The article concludes with speculations about future trends in current and prospective lowest‐low‐fertility countries.     

Modernity and the Contingency of the Public

The idea of a public contingent on its participants is the analogue of resonance to music because neither would make sense without the other. This article introduces the concept of modernity as a framing device and explains the occlusion of the private by the public. Secondly, the article illustrates the Legal-Autonomous Public Model, and the Multiple Public Model in the work of John Dewey, Walter Lippmann, and Kenneth J. Arrow. Public space is what Foucault was alleged to have called '´ecriture', which refers to a convergence of and intermixing of signifiers within a de-gendered setting (hence ´ecriture, as opposed to l'´ecriture). The great contest between Lippmann and Dewey in the 1920s signified a clashing of the two interpretations of the public with one arguing about the need for a return to a constitutionally guaranteed, left-of-centre public philosophy that would entertain the elite while taking care of the poor, and the other a plea for a rationalistic recourse that surmised and envisaged rational public discourse as only one of several possible publics. The article concludes with the notion that the constructions of public space defined by Dewey, Lippmann, and Arrow promote distinct yet related interrogations of public space that is more than an agora of resonating ideas, but includes a kind of automatic reverberation on its own axes.     

Active Employment Policies in Europe

In this paper the authors examine the theoretical framework of the set of laws, provisions, regulations, recommendations and pronouncements that embody the active employment policies in Europe. They illustrate that the theoretical framework is influenced in its attribution of meaning and significance to its subject matter by its relationship with the definitions of employment. To do this they provide an analysis of: the collective agencies, the courses of action, the recipient groups, the relations between the collective agencies, the courses of action decided upon and their recipient subjects, the supporting measures by which these courses of action will be implemented.     

Book Review: Barbara Hobson (ed.), Recognition Struggles and Social Movements,Cambridge University Press,Cambridge, UK,and New York, 2003, 337 pp., bibliography,notes, $27.00

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations -