Adaptive Priors based on Splines with Random Knots

Splines are useful building blocks when constructing priors on nonparametric models indexed by functions. Recently it has been established in the literature that hierarchical priors based on splines with a random number of equally spaced knots and random coefficients in the B-spline basis corresponding to those knots lead, under certain conditions, to adaptive posterior contraction rates, over certain smoothness functional classes. In this paper we extend these results for when the location of the knots is also endowed with a prior. This has already been a common practice in MCMC applications, where the resulting posterior is expected to be more "spatially adaptive", but a theoretical basis in terms of adaptive contraction rates was missing. Under some mild assumptions, we establish a result that provides sufficient conditions for adaptive contraction rates in a range of models

Dimension Estimation Using Random Connection Models

Information about intrinsic dimension is crucial to perform dimensionality reduction, compress information, design efficient algorithms, and do statistical adaptation. In this paper we propose an estimator for the intrinsic dimension of a data set. The estimator is based on binary neighbourhood information about the observations in the form of two adjacency matrices, and does not require any explicit distance information. The underlying graph is modelled according to a subset of a specific random connection model, sometimes referred to as the Poisson blob model. Computationally the estimator scales like n log n, and we specify its asymptotic distribution and rate of convergence. A simulation study on both real and simulated data shows that our approach compares favourably with some competing methods from the literature, including approaches that rely on distance information

Rate-optimal Bayesian intensity smoothing for inhomogeneous Poisson processes

We apply nonparametric Bayesian methods to study the problem of estimating the intensity function of an inhomogeneous Poisson process. We exhibit a prior on intensities which both leads to a computationally feasible method and enjoys desirable theoretical optimality properties. The prior we use is based on B-spline expansions with free knots, adapted from well-established methods used in regression, for instance. We illustrate its practical use in the Poisson process setting by analyzing count data coming from a call centre. Theoretically we derive a new general theorem on contraction rates for posteriors in the setting of intensity function estimation. Practical choices that have to be made in the construction of our concrete prior, such as choosing the priors on the number and the locations of the spline knots, are based on these theoretical findings. The results assert that when properly constructed, our approach yields a rate-optimal procedure that automatically adapts to the regularity of the unknown intensity function

La confusión entre información y publicidad: el caso de las revistas

La ética periodística se basa en valores establecidos hace mucho como la responsabilidad, la libertad, la independencia, la veracidad, la exactitud, la imparcialidad y el fair-play (ASNE, 1922). Y, también, en dos distinciones fundamentales: noticias/ opinión y contenido editorial/publicidad. El reconocimiento de esta teoría ética no impide, sin embargo, que los medios transmitan material que confunde no solo las noticias con la opinión sino también el contenido editorial con la publicidad, como ha sido evidenciado por las críticas de algunos autores (Herman y Chomsky, 1998; Stauber Y Rampton, 2004). La práctica de advertorials es particularmente común en varios tipos de revistas - las revistas de "lo social", "especializadas", pero también "generales" o "informativas" - y en materias que tratan temas como la moda, los coches, vinos, libros, viajes, etc .. Se aplica también a todos estos tipos de productos lo que Luhmann (2000: 70) dice acerca de la moda: “La publicidad, en cuanto texto y en cuanto imagen, se remite a la información”. Para estudiar la frecuencia relativa y los procesos de este tipo de prácticas procedemos a un análisis de una muestra de las revistas Única (Expresso), Tabu (Sol), Visão y Focus.Journalism ethics is based upon long-established values such as responsibility, freedom, independence, truthfulness, accuracy, impartiality and fair-play (ASNE, 1922). And also upon two fundamental distinctions: between news and opinion, and between editorial content and advertising. However, the recognition of this ethical principle does not prevent that mass media convey material that confuses not only news with opinion but also the editorial content with advertising, as evidenced by the criticism of several authors (e.g. Herman and Chomsky, 1998; Stauber and Rampton, 2004). The practice of "advertorial" is particularly common not only in the magazines of the "social" and the "specialized" magazines, but also in the "general" or "informative" magazines; and in materials that address topics such as fashion, cars, wines, books, travels, etc. .. It also applies to all these types of products what Luhmann (2000: 70) says about fashion: "Advertising, as text and as image, refers to information" . To study the relative frequency and the processes of this type of practice we did a content and discourse analysis of a sample of the major Portuguese magazines Única (Expresso newspaper), Tabu (Sol newspaper), Visão and Focus

O espaço ibero-americano de ciências da comunicação e as epistemologias do Sul

This article addresses the relationship between the Ibero-American space of communication sciences and epistemologies of the South, raising the question of whether research in this space tends to approach the epistemological South. To answer the question, firstly, the historical and conceptual context of the epistemologies of the South is outlined, and then the main results of an empirical study of an exploratory nature are presented, based on a bibliometric and textual analysis of a significant sample of journals. The main conclusion is that research in communication sciences in the Ibero-American space approaches, in several aspects, the conception of a post-abyssal science proposed by the epistemologies of the South.O tema deste artigo é a relação entre o espaço ibero-americano de ciências da comunicação e as epistemologias do Sul, levantando a questão de saber se a investigação nesse espaço tende a se aproximar do Sul epistemológico. Para responder à questão, faz-se, em primeiro lugar, a contextualização histórica e conceitual das epistemologias do Sul, apresentando, depois, os principais resultados de um estudo empírico de caráter exploratório, baseado numa análise bibliométrica e textual de uma amostra significativa de revistas. Conclui-se que a investigação em ciências da comunicação no espaço ibero-americano se aproxima, em vários aspetos, da concepção de uma ciência pós-abissal proposta pelas epistemologias do Sul

Tourism Demand in Portugal: Market Perspectives

Tourism has experienced different levels of development in the different regions of Portugal. To frame this development, several panel data models were estimated. The main objective is to explain the evolution of overnight stays by nationality in each region. Secondary data from 2000 to 2010 was used. The analysis includes the main tourism markets, such as the United Kingdom, Germany, the Netherlands, Ireland, France and Spain. Tourism literature suggests that, among others, the main determinants of tourism demand are Income (GDP), population, tourist´s income by place of residence, households’ consumption, unemployment rate, inflation rate, compensation of employees, comparative prices and households’ investment rate. It is observed that, although significant, the explanatory power of these variables varies according to the origin and the destination region considered

Beyond propaganda and the Internet: the ethics of journalism

According to Herman and Chomsky’s “propaganda model”, the information conveyed by the news media is largely determined, both with regard to the agenda-setting and the framing of the news, by the “persuasion industries”. Unlike those media, the Internet offers, at least for now, the possibility that different, alternative voices of citizens and civic and non-governmental organizations are freely heard. At the same time, the Internet challenges the monopoly of traditional news media to offer relevant, credible information. This possibility of citizens and organizations to use Internet to oppose to propaganda is, probably, one of the causes of the current crisis of journalism. The survival of journalism to this crisis lies not in forgetting its ethics but rather in the systematic and consistent reaffirmation of that ethics. Thus, ethics reveals itself as a necessary condition, even if not a sufficient one, to the pragmatic success of journalism

Corticeira Amorim: uncorking the future: converting a cork stoppers business into a knowledge company – An organizational and strategic evolution –

Corticeira Amorim is, for many years, the worldwide leader in cork manufacturing, setting the pace and pointing the way forward in its sector. However, in the late 1990s, cork stoppers market, since always the company’s main product, was very seriously threatened due to the emergence of a strong substitute – the plastic stopper – ready to dethrone the cork stopper. The two main reasons for its emergence were a huge increase in the cork price, which tripled between 1994 and 2000, and growing customers’ complaints about TCA, deemed responsible for damaging the taste of wine in bottles using cork stoppers. This instigated an organizational and strategic change at Corticeira Amorim in the beginning of the 21st century, converting it from a cork stoppers business into a knowledge company, committed to add value to cork no matter the format. The fact that the company, despite its big size, is a family owned business has played an important role in its evolution and strategic options, throughout its whole history and notably in this critical moment, which denotes a long term concern and deserves analysis. The strong investment in R&D and Innovation, and the growing recognition of knowledge, in its different forms, as a potential source of competitive advantage, also in usually less high-tech sectors, is another perspective to be discussed. This context was the basis for the preparation of a pedagogical case study and teaching note. The case was field based, notably with interviews, as primary data source, and also compiled from published sources, as secondary date source. It is intended to be used as the basis for class discussion rather than as an endorsement, source of primary data or illustration of the effective or ineffective handling of a management situation

Adaptive empirical Bayesian smoothing splines

In this paper we develop and study adaptive empirical Bayesian smoothing splines. These are smoothing splines with both smoothing parameter and penalty order determined via the empirical Bayes method from the marginal likelihood of the model. The selected order and smoothing parameter are used to construct adaptive credible sets with good frequentist coverage for the underlying regression function. We use these credible sets as a proxy to show the superior performance of adaptive empirical Bayesian smoothing splines compared to frequentist smoothing splines