Rosa M. Crujeiras

• Doctor of Philosophy
• Professor (Associate) at University of Santiago de Compostela

Otolith microchemistry analysis revealed that bycatch of European shads - allis shad Alosa alosa (L. 1758) and twaite shad Alosa fallax (Lacepede 1803) - in western Iberian commercial fisheries removes individuals from a wide array of natal origins, with the most abundant source rivers suffering the heaviest losses. Spatial variation in bycatch ris...

Nonparametric regression models involving circular variables (as responses and/or covariates) are revised in this chapter, focusing on a kernel approach. For linear response and circular covariate, both suitably adapted local polynomial and local likelihood models are introduced. The local polynomial approach is also presented for circular response...

Modal regression has emerged as a flexible alternative to classical regression models when the conditional mean or median are unable to adequately capture the underlying relation between a response and a predictor variable. This approach is particularly useful when the conditional distribution of the response given the covariate presents several mo...

The modes of a statistical population are high frequency points around which most of the probability mass is accumulated. For the particular case of circular densities, we address the problem of testing if, given an observed sample of a random angle, the underlying circular distribution model is multimodal. Our work is motivated by the analysis of...

A statistical hypothesis test for long range dependence (LRD) in manifold-supported functional time series is formulated in the spectral domain. The proposed test statistic operator is based on the weighted periodogram operator. It is assumed that the elements of the spectral density operator family are invariant with respect to the group of isomet...

Given a random sample from a density function supported on a manifold M, a new method for the estimating highest density regions of the underlying population is introduced. The new proposal is based on the empirical version of the opening operator from mathematical morphology combined with a preliminary estimator of density function. This results i...

The modes of a statistical population are high frequency points around which most of the probability mass is accumulated. For the particular case of circular densities, we address the problem of testing if, given an observed sample of a random angle, the underlying circular distribution model is multimodal. Our work is motivated by the analysis of...

The anadromous clupeid allis shad, Alosa alosa (Linnaeus, 1758), and twaite shad, Alosa fallax (Lacépède, 1803), collectively called European shads, are diadromous fish migrating between their reproduction areas in rivers and marine feeding grounds. Both species are in decline due to cumulative impacts of human activities across their life cycle. A...

Stop discriminación. EVALUACIÓN DE LA APLICACIÓN DE LA LEY 14/2011 DE LA CIENCIA EN LO REFERENTE A LA PERSPECTIVA DE GÉNERO. PROPUESTAS DE MEJORA

The study of how the number of spikes in a middle temporal visual area (MT/V5) neuron is tuned to the direction of a visual stimulus has attracted considerable attention over the years, but recent studies suggest that the variability of the number of spikes might also be influenced by the directional stimulus. This entails that Poisson regression m...

Personalized medicine in cancer treatment is based on knowledge of the RNA levels of a set of genes that are deregulated as a consequence of the pathology. Hence, knowledge of the gene expression profiles of tumours in cancer patients allows optimal treatments to be applied. One of the main challenges when classifying patients based on gene express...

The directional wave spectrum (DWS) describes the energy of sea waves as a function of frequency and direction. It provides useful information for marine studies and guides the design of maritime structures. One of the challenges in the statistical estimation of DWS is to account for the circular nature of direction. To address this issue, this pap...

Changes on temperature patterns, on a local scale, are perceived by individuals as the most direct indicators of global warming and climate change. As a specific example, for an Atlantic climate location, spring and fall seasons should present a mild transition between winter and summer, and summer and winter, respectively. By observing daily tempe...

Analyzing the escape direction of animals subject to covariates is a problem that requires statistical techniques beyond classical regression methods. Apart from the periodicity of the angle of direction, which demands the use of circular statistics, animal escape data usually call for the exploration of the preferred orientations rather than the e...

A sizable amount of goodness-of-fit tests involving functional data have appeared in the last decade. We provide a relatively compact revision of most of these contributions, within the independent and identically distributed framework, by reviewing goodness-of-fit tests for distribution and regression models with functional predictor and either sc...

This paper presents a general framework for the estimation of regression models with circular covariates, where the conditional distribution of the response given the covariate can be specified through a parametric model. The estimation of the conditional mean, or a transformation of it, is carried out nonparametrically, by maximizing the circular...

Choice models (CM) are proposed in the field of tourism recommender systems (TRS) with the aim of providing algorithms with both a theoretical understanding of tourist's motivations and a certain degree of transparency. The goal of this work is to overcome some of the limitations of current state‐of‐art algorithms used in TRSs by providing: (1) acc...

Distance-decay models fit parametric functions to assess the relationship between similarity and spatial or environmental distance. Despite being a widely used method in ecology, no method has been previously developed and validated to assess the significance of differences between the parameters (i.e. intercept and slope) of two distance-decay mod...

Allis shad, Alosa alosa (Linnaeus, 1758), and twaite shad, Alosa fallax (Lacépède, 1803), are two anadromous fish species belonging to the family Clupeidae. Like all other diadromous species, their populations in European rivers are in decline and their scarcity has become an emerging problem. Anthropogenic activities, mainly large dams and other r...

Modeling circular distributions in a flexible and meaningful way has been the motivation for a prolific topic within circular statistics. Flexible distribution models aim to capture not only location or concentration features, but also peakedness and skewness, and one may consider nonparametric approaches (such as kernel method) for that purpose. H...

Changes on temperature patterns, on a local scale, are perceived by individuals as the most direct indicators of global warming and climate change. As a specific example, for an Atlantic climate location, spring and fall seasons should present a mild transition between winter and summer, and summer and winter, respectively. By observing daily tempe...

The determination of background pollution levels is fundamental for the interpretation of the results obtained from environmental biomonitoring. In this paper we propose a new probabilistic method, based on a Gaussian mixture model, for determining the distribution of regional background levels of different pollutants. The distribution of the refer...

Aim (i) To assess the dependence between the form of the decrease in biological similarity with distance (distance‐decay) and species range size and (ii) to introduce the use of a sigmoidal model, the Gompertz function, as a flexible alternative able to fit distance‐decay models under a wide variety of species range sizes. Location Applicable worl...

Aim Modelling how community similarity decays with spatial distance is a key tool for the study of the processes behind community variation (beta diversity). Distance‐decay models are computed from pairwise metrics (i.e. community similarity and spatial distance between localities) and hence suffer from pairwise dependence in the data, precluding t...

Este trabajo revisa la aplicación de la Ley 14/2011, de 1 de junio, de la Ciencia, la Tecnología y la Innovación, en lo referente a la disposición adicional decimotercera de la ley relativa a la implantación de la perspectiva de género. En concreto, analiza y evalúa su aplicación en distintos ámbitos que comprenden la selección y evaluación del per...

Testing procedures for assessing a parametric regression model with a circular response and an Rd-valued covariate are proposed and analysed in this work. The test statistics are based on a circular distance comparing a (non-smoothed or smoothed) parametric circular regression estimator and a nonparametric one. Two bootstrap procedures for calibrat...

The analysis of continuously spatially varying processes usually considers two sources of variation, namely, the large-scale variation collected by the trend of the process, and the small-scale variation. Parametric trend models on latitude and longitude are easy to fit and to interpret. However, the use of parametric models for characterizing spat...

Highest density regions (HDRs) are defined as level sets containing sample points of relatively high density. Although Euclidean HDR estimation from a random sample, generated from the underlying density, has been widely considered in the statistical literature, this problem has not been contemplated for directional data yet. In this work, directio...

Stop discrimination: Gender-sensitive proposals for the effective application of the Spanish Law on Science, Technology and Innovation This work critically reviews the implementation of gender perspective in the regulation of scientific and technological research in Spain. It focuses on the application of Law 14/2011, of June 1, on Science, Technol...

Goodness-of-fit tests for quantile regression models, in the presence of missing observations in the response variable, are introduced and analysed in this paper. The different proposals are based on the construction of empirical processes considering three different approaches which involve the use of the gradient vector of the quantile function,...

A sizable amount of goodness-of-fit tests involving functional data have appeared in the last decade. We provide a relatively compact revision of most of these contributions, within the independent and identically distributed framework, by reviewing goodness-of-fit tests for distribution and regression models with functional predictor and either sc...

In oceanography, modeling wave fields requires the use of statistical tools capable of handling the circular nature of the data measurements. An important issue in ocean wave analysis is the study of height and direction waves, being direction values recorded as angles or, equivalently, as points on a unit circle. Hence, reconstruction of a wave di...

Multimodal regression estimation methods are introduced for regression models involving circular response and/or covariate. The regression estimators are based on the maximization of the conditional densities of the response variable over the covariate. Conditional versions of the mean shift and the circular mean shift algorithms are used to obtain...

Nonparametric estimators of a regression function with circular response and Rd-valued predictor are considered in this work. Local polynomial estimators are proposed and studied. Expressions for the asymptotic conditional bias and variance of these estimators are derived, and some guidelines to select asymptotically optimal local bandwidth matrice...

Reconstruction of sets from a random sample of points intimately related to them is the goal of set estimation theory. Within this context, a particular problem is the one related with the reconstruction of density level sets and specifically, those ones with a high probability content, namely highest density regions. We define highest density regi...

No matter the nature of the response and/or explanatory variables in a regression model, some basic issues such as the existence of an effect of the predictor on the response, or the assessment of a common shape across groups of observations, must be solved prior to model fitting. This is also the case for regression models involving circular varia...

Testing procedures for assessing a parametric regression model with circular response and $\mathbb{R}^d$-valued covariate are proposed and analyzed in this work both for independent and for spatially correlated data. The test statistics are based on a circular distance comparing a (non-smoothed or smoothed) parametric circular estimator and a nonpa...

Stop discriminación. EVALUACIÓN DE LA APLICACIÓN DE LA LEY 14/2011 DE LA CIENCIA EN LO REFERENTE A LA PERSPECTIVA DE GÉNEROPRO. PROPUESTAS DE MEJORA

The abundance of Atlantic salmon in Europe has declined throughout its native range. One of the main causes is low marine survival, which has been mainly attributed to overexploitation at sea, but global warming, decreased zooplankton abundance in the North Atlantic and local changes in freshwater conditions have been also blamed. It has been also...

Background Asthma is heterogeneous disease with different phenotypes, endotypes and severities. Definition of these subgroups requires the identification of biomarkers in biological samples, and serum proteomics is a useful and minimally invasive method for this purpose. Therefore, the aim of this study was to detect serum proteins whose abundance...

The analysis of continuously spatially varying processes usually considers two sources of variation, namely, the large-scale variation collected by the trend of the process, and the small-scale variation. Parametric trend models on latitude and longitude are easy to fit and to interpret. However, the use of simple parametric models for characterizi...

Nonparametric estimators of a regression function with circular response and Rd-valued predictor are considered in this work. Local polynomial estimators are proposed and studied. Expressions for their asymptotic biases and variances are derived, and some guidelines to select asymptotically local optimal bandwidth matrices are also given. The finit...

Understanding the role of vegetation fires in the Earth system is an important environmental problem. Although fire occurrence is influenced by natural factors, human activity related to land use and management has altered the temporal patterns of fire in several regions of the world. Hence, for a better insight into fires regimes it is of special...

Nonparametric tests for circular regression models (models where the response and/or the covariate are circular variables) are introduced and analysed in this work. Based on nonparametric smoothers for estimating regression curves, no-effect tests are first introduced. Nonparametric Analysis of Covariance (ANCOVA) models are also stated in the circ...

The problem of assessing a parametric regression model in the presence of spatial correlation is addressed in this work. For that purpose, a goodness-of-fit test based on a L2-distance comparing a parametric and nonparametric regression estimators is proposed. Asymptotic properties of the test statistic, both under the null hypothesis and under loc...

Non-parametric regression with a circular response variable and a unidimensional linear regressor is a topic which was discussed in the literature. In this work, we extend the results to the case of multivariate linear explanatory variables. Nonparametric procedures to estimate the circular regression function are formulated. A simulation study is...

The one-century-old theory of orthogonal genetic variance decomposition originated the field of quantitative genetics and has kept on being improved ever since. Recently, serious concerns about the possibility of attaining a satisfactory implementation of genetic variance decomposition with linkage disequilibrium (LD) and epistasis have been raised...

This article presents PDMapping, a new tool developed to assist the collecting and processing of data in research projects in Perceptual Dialectology. It allows information to be stored in a structured database and processed easily using either quantitative analysis-based statistical software or Geographic Information Systems (GIS). After presentin...

Understanding the role of vegetation fires in the Earth system has become an important environmental problem. Although fires time occurrence is mainly influenced by climate, human activity related with land use and management has altered fire patterns in several regions of the world. Hence, for a better insight in fires regimes, it is of special in...

The aim of this work is to propose and analyze the behavior of a test statistic to assess a parametric trend surface, that is, a regression model with spatially correlated errors. The asymptotic behavior under the null hypothesis, as well as the asymptotic power of the test under local alternatives will be analyzed. Finite sample performance of the...

En la caracterización de la población de una región geográfica, el estudio de los apellidos se presenta como una fuente importante de información. En este trabajo, el objetivo es el modelado espacial del patrón que siguen los apellidos en Asturias. Para ello, se ha estudiado la isonimia en la región, analizando los apellidos de 858.662 personas (da...

PurposeThe main purpose of this article is to assess the environmental impacts associated with the fishing operations related to European anchovy fishing in Cantabria (northern Spain) under a life cycle approach. Methods The life cycle assessment (LCA) methodology was applied for this case study including construction, maintenance, use, and end of...

Testing procedures for assessing specific parametric model forms, or for checking the plausibility of simplifying assumptions, play a central role in the mathematical treatment of the uncertain. No certain answers are obtained by testing methods, but at least the uncertainty of these answers is properly quantified. This is the case for tests design...

In several applied fields, multimodality assessment is a crucial task as a previous exploratory tool or for determining the suitability of certain distributions. The goal of this paper is to present the utilities of the R package multimode, which collects different exploratory and testing nonparametric approaches for determining the number of modes...

In several applied fields, multimodality assessment is a crucial task as a previous exploratory tool or for determining the suitability of certain distributions. The goal of this paper is to present the utilities of the R package multimode, which collects different exploratory and testing nonparametric approaches for determining the number of modes...

Purpose Life cycle assessment (LCA) and data envelopment analysis (DEA) have been combined in numerous occasions in order to identify the environmental efficiency of multiple units. In many cases, important differences in environmental performance have been identified among the units, referred to as decision-making units (DMUs). However, most studi...

Testing procedures for assessing specific parametric model forms, or for checking the plausibility of simplifying assumptions, play a central role in the mathematical treatment of the uncertain. No certain answers are obtained by testing methods, but at least the uncertainty of these answers is properly quantified. This is the case for tests design...

The thermal response of soils in cold environments has been investigated in numerous studies. The data considered here were obtained in a study carried out in Tierra del Fuego, Argentina, as part of the IV International Polar Year. Temperature sensors were installed at ground level (0) and depths of -10, -20 and -60 cm in the study area, with the a...

Creating an ideal environment to develop creativity and innovation in engineering education is a real challenge. One alternative approach can be based in the application of Gamestorming methodology that considers the use of games in the process of brainstorming. Presenting the problem in a game format eludes the conventional lecturing and frees the...

This is the editorial letter for the Special Issue dedicated to the VIII International Workshop on Spatio-temporal Modelling (METMAVIII) which took place in Valencia (Spain) from 1 to 3 June 2016, and to the second Galician-Portuguese meeting of Biometry, with applications to Health Sciences, Ecology and Environmental Sciences (BIOAPP2016) held in...

The trajectory of an interdisciplinary project on dialectal perceptions, within the research network TecAnDaLi is reviewed in this paper. Advances from technical, linguistic and statistical perspectives are described as a consequence of the interaction between different disciplines, from data collection to modelling approaches.

Motivated by studies of wildfire seasonality, we propose a nonhomogeneous hidden Markov random field to model the spatial distribution of georeferenced fire occurrences during the year, by representing occurrence times as circular data. The model is based on a mixture of Kato–Jones circular densities, whose parameters vary across space according to...

Angles, directions, events, occurrences along time... all of them can be viewed as data on a circle (circular data). The particular nature of this type of data requires specific and adapted inferential and modelling procedures. Although there are quite a few references on this topic, and despite circular data are quite common in many applied scienc...

Questions Once effects of hydrological and chemical soil properties have been accounted for, does soil microbial diversity contribute to explain change in plant community structure (i.e. within‐site β‐diversity)? If so, at what spatial scale does microbial diversity operate? Location La Mina in Moscosa Farm, Salamanca, western Spain ( dehesa commu...

The identification of peaks or maxima in probability densities, by mode testing or bump hunting, has become an important problem in applied fields. This task has been approached in the statistical literature from different perspectives, providing testing procedures which are based on kernel density estimators or on the quantification of excess mass...

The identification of peaks or maxima in probability densities, by mode testing or bump hunting, has become an important problem in applied fields. This task has been approached in the statistical literature from different perspectives, with the proposal of testing procedures which are based on kernel density estimators or on the quantification of...

Objectives: Since 2011, smoking legislation was hardened in Spain, banning tobacco consumption in all hospitality venues. Law 42/2010 was the first comprehensive tobacco control policy enacted in Spain. The aim of this paper is to evaluate the effect that this intervention has had in reducing the prevalence of tobacco consumption, setting up three...

This work presents a contribution to the question of how to develop data processing (both technically & statistically) in perceptual dialectology (PD) studies. This discipline focuses on the study of non-linguists perceptions of dialectal variation. Such tasks require a large amount of information whose treatment can be improved if suitable tools f...

Acknowledgement of the age effects on postural control and balance is essential to differentiate between physiological changes and actual pathological alterations of the elderly. The aim of this study is to establish the age-related postural changes recorded by the Computerized Dynamic Posturography. 70 healthy individuals (35 males and 35 females)...

O emprego de programas de imputación xenética forma parte da práctica habitual en estudos de asociación xenética e meta-análises, xa que o panel de SNPs xenotipados varía en función da plataforma comercial utilizada en cada caso. Aínda que estes programas achegan o xenotipo individual para o SNP de interese, o dato necesario para as análises poster...

Plant community ecologists use the null model approach to infer assembly processes from observed patterns of species co-occurrence. In about a third of published studies, the null hypothesis of random assembly cannot be rejected. When this occurs, plant ecologists interpret that the observed random pattern is not environmentally constrained – but p...

Nonparametric density and regression estimation methods for circular data are included in the R package NPCirc. Specifically, a circular kernel density estimation procedure is provided, jointly with different alternatives for choosing the smoothing parameter. In the regression setting, nonparametric estimation for circular-linear, circular-circular...

Wildfires represent a threat to natural resources, causing a huge economic and environmental damage, so an effective management of wildfires is required in order to avoid devastating effects. Preventive policies recommend fuel management practices at landscape level, but these measurements will only be successful if strategically placed in order to...

This paper presents a goodness-of-fit test for parametric regression models with scalar response and directional predictor, that is, vectors in a sphere of arbitrary dimension. The testing procedure is based on the weighted squared distance between a smooth and a parametric regression estimator, where the smooth regression estimator is obtained by...

A central limit theorem for the integrated squared error of the directional-linear kernel density estimator is established. The result enables the construction and analysis of two testing procedures based on the squared loss: a nonparametric independence test for directional and linear random variables and a goodness-of-fit test for parametric fami...

A minimum contrast criterion for consistently estimating the spatial fractal dimension in the wavelet domain is presented in [M. D. Ruiz-Medina and R. M. Crujeiras, Comm. Statist. Theory Methods., 40 (2011), pp. 3599–3613] for a class of semiparametric fractal Gaussian random fields, which includes fractional Brownian motion and Riesz-Bessel motion...

Surnames (family names) can be used as a source of information for population charac- teristics, given that the analysis of surname patterns provides information about long{ term and short{term dynamics of population movements. With the aim of identifying surname patterns, specially regionalized concentrations, di�erent isonymy measures be- tween r...

The empirical variogram is a standard tool in the investigation and modelling of spatial covariance. However, its properties can be difficult to identify and exploit in the context of exploring the characteristics of individual datasets. This is particularly true when seeking to move beyond description towards inferential statements about the struc...

First for all, we would like to thank the discussants for reading our paper and fortaking time to prepare such interesting and valuable contributions. The feeling, afterrevising the discussions and going back to the original version of the paper, is thatthere is still too much to say about Goodness-of-Fit (GoF) tests for regression modelsand the di...