Design-based random permutation models with auxiliary information

We extend the random permutation model to obtain the best linear unbiased estimator of a finite population mean accounting for auxiliary variables under simple random sampling without replacement (SRS) or stratified SRS. The proposed method provides a systematic design-based justification for well-known results involving common estimators derived under minimal assumptions that do not require specification of a functional relationship between the response and the auxiliary variables.     

Hierarchical Variable Selection in Polynomial Regression Models

Significance tests on coefficients of lower-order terms in polynomial regression models are affected by linear transformations. For this reason, a polynomial regression model that excludes hierarchically inferior predictors (i.e., lower-order terms) is considered to be not well formulated. Existing variable-selection algorithms do not take into account the hierarchy of predictors and often select as “best” a model that is not hierarchically well formulated. This article proposes a theory of the hierarchical ordering of the predictors of an arbitrary polynomial regression model in m variables, where m is any arbitrary positive integer. Ways of modifying existing algorithms to restrict their search to well-formulated models are suggested. An algorithm that generates all possible well-formulated models is presented.     

Innovation through tradition in the Italian coffee industry: an analysis of customers’ perceptions

The extant literature reveals how firms may innovate by exploiting past competencies and resources, hence proposing innovation through tradition as an emerging strategy to compete. Previous research largely demonstrates that the effectiveness of an innovation strategy is strictly dependent on the capability of firms to communicate the right message to their customers. Therefore, leveraging products’ attributes becomes fundamental to strategically position their commercial offerings in the minds of the target audience. Nevertheless, despite the well-known relevance of this issue, scant attention has been devoted to investigate the product attributes that consumer’s associate with innovation and with tradition when companies deploy strategies based on “innovation through tradition”. Accordingly, our study aims at covering this gap, by empirically analyzing the consumers’ perception of innovation and tradition in the Italian coffee industry through a positioning analysis. Our research allowed us to identify two sets of product attributes that consumers associate with innovation and tradition. The results show that in many cases the innovation-related and tradition-related attributes are strongly negatively correlated, but in some case the correlation is weak or close to zero. These attributes reveal that in some cases innovation and tradition can be combined in the perception of consumers, rather than representing opposite constructs. This result suggests that companies can effectively communicate the strategy of innovation through tradition to the consumers’ minds, but this must be done by choosing the right attributes.     

From Entrepreneurial Orientation and Learning Orientation to Business Performance: Analysing the Mediating Role of Organizational Learning and the Moderating Effects of Organizational Size

Following the organizational learning theory and the knowledge‐based view approach, this contribution aims to study the influence of entrepreneurial orientation and learning orientation on organizational learning, considering the latter as a mediating variable in the relationships between both antecedent cultural values and business performance. We also analyse the moderating role of organizational size on these previous relationships. The hypotheses proposed in our research model are tested on a sample of 140 Spanish industrial companies, applying variance‐based structural equation modelling: partial least squares. In order to assess the moderating effects of organizational size, we adopt a multi‐group approach using two subsamples with large firms and small and medium‐sized enterprises (SMEs). Our findings indicate that organizational learning partially mediates the relationship between entrepreneurial orientation and performance and fully mediates the link between learning orientation and performance. Likewise, the results reveal that the relationship established between entrepreneurial orientation and organizational learning is more intense for the group of large firms than for the group of SMEs. Moreover, the influence of learning orientation on organizational learning is greater in SMEs than in large firms.     

Ownership Structure,Corporate Value and Firm Investment: A Simultaneous Equations Analysis of Spanish Companies

This paper is concerned with the set of mutualrelationships between firm valuation andinvestment, and with the possible endogeneityof ownership structure. In order to deal withthem properly, we aim to test the mutual impactof investment, corporate value and ownership bybroadening the usual framework with asimultaneous equations approach. Using a sampleof 140 Spanish listed companies for the1991–1997 period, we have found that,consistent with previous research, thealignment and entrenchment hypotheses seem tobe confirmed by the estimation of aone-equation model. However, when analyzed bymeans of a system of simultaneous equations inwhich a set of mutual relationships isintroduced, quite different results wereobtained. Although valuation and investment offirms are determined by managerial ownership,we have found that ownership structure may alsobe influenced both by investment and value.Consequently, it is not completely right toinfer that ownership structure determines firmvalue unidirectionally; however the benchmarkshould be broadened so as to take an explicitaccount of the mutual links between firm value,investment and ownership.     

Estimation of the mean quality-adjusted survival using a multistate model for the sojourn times

In clinical trials, it may be of interest taking into account physical and emotional well-being in addition to survival when comparing treatments. Quality-adjusted survival time has the advantage of incorporating information about both survival time and quality-of-life. In this paper, we discuss the estimation of the expected value of the quality-adjusted survival, based on multistate models for the sojourn times in health states. Semiparametric and parametric (with exponential distribution) approaches are considered. A simulation study is presented to evaluate the performance of the proposed estimator and the jackknife resampling method is used to compute bias and variance of the estimator.     

Accuracy of edge detection methods with local information in speckled imagery

We compare the accuracy of five approaches for contour detection in speckled imagery. Some of these methods take advantage of the statistical properties of speckled data, and all of them employ active contours using B-spline curves. Images obtained with coherent illumination are affected by a noise called speckle, which is inherent to the imaging process. These data have been statistically modeled by a multiplicative model using the G0 distribution, under which regions with different degrees of roughness can be characterized by the value of a parameter. We use this information to find boundaries between regions with different textures. We propose and compare five strategies for boundary detection: three based on the data (maximum discontinuity on raw data, fractal dimension and maximum likelihood) and two based on estimates of the roughness parameter (maximum discontinuity and anisotropic smoothed roughness estimates). In order to compare these strategies, a Monte Carlo experience was performed to assess the accuracy of fitting a curve to a region. The probability of finding the correct edge with less than a specified error is estimated and used to compare the techniques. The two best procedures are then compared in terms of their computational cost and, finally, we show that the maximum likelihood approach on the raw data using the G0 law is the best technique.     

Bayesian assessment of times to diagnosis in breast cancer screening

Breast cancer is one of the diseases with the most profound impact on health in developed countries and mammography is the most popular method for detecting breast cancer at a very early stage. This paper focuses on the waiting period from a positive mammogram until a confirmatory diagnosis is carried out in hospital. Generalized linear mixed models are used to perform the statistical analysis, always within the Bayesian reasoning. Markov chain Monte Carlo algorithms are applied for estimation by simulating the posterior distribution of the parameters and hyperparameters of the model through the free software WinBUGS.     

Land,territory and commons: voices and visions from the struggles

ABSTRACT

All over the world, financial capitalism and extractivism are appropriating land as if it was nothing more than a commodity, a mere ‘factor’ of production that can be exploited to generate financial returns. Movements and activists are organizing, resisting, protecting and promoting life-giving visions against this continuous enclosure of living beings and paces: they use their bodies, laws, educational projects, histories and visions to regain control over territory as a political space, self-determine and create solidarities. In the act resistance, they are the target of moral, physical and legal violence. They and their ideas are criminalized, disciplined, punished and in some cases exterminated. In this contribution, activists from the Basque Country, Guatemala, Kenya and the Six Nations and a group of academics get together to learn from each other, support the ongoing search for common vocabularies and identify possible milestones of a coordinated and international strategy for a life-enhancing future.     

Racialisation and racial formation in urban spaces*

ABSTRACT

In this paper, I try to clarify the notions of racialisation and racial formation and how they operate in the framework of nation states like Brazil. My main argument is that these processes are always constrained by the formation of social classes and national cultural repertoires even if transnational forces are important in nurturing them. I conclude by making a preliminary effort to unravel mechanisms and institutions which allow these processes of racialisation and racial formation to form part of the daily lives of black Brazilians in the context of class-structured urban spaces.