Jose Luis Vicente Villardon

• Mathematics-Statistics
• Professor (Full) at University of Salamanca

Biplot Methods allow for the simultaneous representation of individuals and variables of a data matrix. For Binary or Nominal data, Logistic biplots have been recently developed to extend the classical linear representations for continuous data. When data are ordinal, linear, binary or nominal logistic biplots are not adequate and techniques as Cat...

Unlabelled: For characterization of genetic diversity in genotypes several molecular techniques, usually resulting in a binary data matrix, have been used. Despite the fact that in Cluster Analysis (CA) and Principal Coordinates Analysis (PCoA) the interpretation of the variables responsible for grouping is not straightforward, these methods are c...

The evolutionary history of crop pathogens is shaped by a complex interaction of natural and anthropogenic factors. The fungus Colletotrichum graminicola causes maize anthracnose which results in significant yield losses worldwide. We conducted a comprehensive investigation into the evolutionary genomics of C. graminicola using a collection of 212...

Classical Partial Least Squares Regression (PLSR) models were developed primarily for continuous data, allowing dimensionality reduction while preserving relationships between predictors and responses. However, their application to binary data is limited. This study introduces Binary Partial Least Squares Regression (BPLSR), a novel extension of th...

Classical Partial Least Squares (PLS) models were developed primarily for continuous data, allowing dimensionality reduction while preserving relationships between predictors and responses. However, their application to binary data is limited. This study introduces Binary Partial Least Squares (BPLS), a novel extension of the PLS methodology design...

Biplots are useful tools because they provide a visual representation of both individuals and variables simultaneously, making it easier to explore relationships and patterns within multidimensional datasets. This paper extends their use to examine the relationship between a set of predictors 𝐗 and a set of response variables 𝐘 using Principal Cova...

In behavioral research, it is very common to have manage multiple datasets containing information about the same set of individuals, in such a way that one dataset attempts to explain the others. To address this need, in this paper the Tucker3-PCovR model is proposed. This model is a particular case of PCovR models which focuses on the analysis of...

The fungal biodiversity associated with a stable plant community appears to vary from year to year. To analyse the annual behaviour in the formation of fruiting bodies, a statistical study of the data obtained for 4 years (2009–2012) in an apparently undisturbed Mediterranean ecosystem dominated by the holm oak (Quercus ilex L. subsp. ballota (Desf...

Understanding the genetic diversity and mechanisms underlying genetic variation in pathogen populations is crucial to the development of effective control strategies. We investigated the genetic diversity and reproductive biology of Colletotrichum graminicola isolates which infect maize by sequencing the genomes of 108 isolates collected from 14 co...

Neuroendocrine tumors (NETs) represent a heterogeneous malignancy group of neoplasms, with a limited amount of data from Latin America. Thus, this observational study aimed to provide data about the prevalence, incidence, and survival rates for NET in Ecuadorian hospitals. The study was conducted using data from the Society for the Fight Against Ca...

In this paper, we propose a generalization of Partial Least Squares Regression (PLS-R) for a matrix of several binary responses and a a set of numerical predictors. We call the method Partial Least Squares Binary Logistic Regression (PLS-BLR). That is equivalent to a PLS-2 model for binary responses. Biplot and even triplot graphical representation...

Background Colletotrichum graminicola , the causal agent of maize anthracnose, is an important crop disease worldwide. Understanding the genetic diversity and mechanisms underlying genetic variation in pathogen populations is crucial to the development of effective control strategies. The genus Colletotrichum is largely recognized as asexual, but s...

Neuroendocrine tumors (NETs) are relative rare, affecting neuroendocrine cells throughout the body. Most tumors are diagnosed at advanced stages. NETs prevalence has increased in the last years but there is little data available in developing countries. The aim of this study was to describe symptoms associated with NETs in patients of the Society f...

The methodology used for the determination of macrofungal diversity in Mediterranean areas differs in the time of sampling and the number of years displayed, making it difficult to compare results. Furthermore, the results could be refuted because the studies are being conducted over an insufficient number of years or without considering the variat...

In recent years, social responsibility has been revolutionizing sustainable development. After the development of new mathematical techniques, the improvement of computers’ processing capacity and the greater availability of possible explanatory variables, the analysis of these topics is moving towards the use of different machine learning techniqu...

Background: Neuroendocrine tumors (NETs) are severe and relatively rare and may affect any organ of the human body. The prevalence of NETs has increased in recent years; however, there seem to be more data on particular types, even though, despite the efforts of different guidelines, there is no consensus on how to identify different types of NETs....

Multivariate binary data are increasingly frequent in practice. Although some adaptations of principal component analysis are used to reduce dimensionality for this kind of data, none of them provide a simultaneous representation of rows and columns (biplot). Recently, a technique named logistic biplot (LB) has been developed to represent the rows...

Background: Systematic screening for antibodies against SARS-CoV-2 is a crucial tool for surveillance of the COVID-19 pandemic. The University of Salamanca (USAL) in Spain designed a project called "DIANCUSAL" (Diagnosis of New Coronavirus, COVID-19, in University of Salamanca) to measure antibodies against SARS-CoV-2 among its ~34,000 students an...

Background: Systematic screening for antibodies against SARS-CoV-2 is a crucial tool for surveillance of the COVID-19 pandemic. The University of Salamanca (USAL) in Spain designed a project called “DIANCUSAL” (Diagnosis of New Coronavirus, COVID-19, in University of Salamanca) to measure antibodies against SARS-CoV-2 among its ~34,000 students and...

Research Highlights: The regeneration of Quercus species is usually very difficult in many oak woodlands transformed by livestock farming. Some studies have reported that shrubs can facilitate regeneration. However, the strength of interaction may vary depending on, among other factors, the shrub species and the stress tolerance of the oak species....

Redundancy Analysis (RDA) is one of the many possible methods to extract and summarize the variation in a set of response variables that can be explained by a set of explanatory variables. The main idea is to use multivariate linear regression to explain the responses as a linear function of the explanatory and then use Principal Component Analysis...

A simultaneous representation of individuals and variables in a data matrix is called a biplot. When variables are binary, nominal, or ordinal, a classical linear biplot representation is not adequate. Recently, biplots for categorical data-based logistic response models have been proposed. The coordinates of individuals and variables are computed...

Premise: Black Sigatoka is one of the most severe banana (Musa spp.) diseases worldwide, but no methods for the rapid early detection of this disease have been reported. This paper assesses the use of hyperspectral images for the development of a partial-least-squares penalized-logistic-regression (PLS-PLR) model and a hyperspectral biplot (HS bip...

Background Specific cognitive alterations could be one of the predictors that lead to the complex activities of daily living (CADL) impairment in mild cognitive impairment (MCI) and, hence, help to explain the continuum between MCI and dementia. Objective We aimed to reevaluate the existing uncertainty regarding the impact of memory and executive...

Currently, it is well established that monocytes are a heterogeneous type of cell consisting of phenotypically and functionally distinct subpopulations found to be numerically altered in blood in patients with a wide variety of disease conditions, such as infection, autoimmunity, respiratory and cardiovascular diseases, and inflammatory disorders.1...

Many food packages on the market show an image of the product contained inside or the ingredients with which the product was produced. During the packaging design process, it is the job of the designer or the marketing team to decide which specific image will be depicted on the packaging. This paper analyses the potential implications of this decis...

We previously demonstrated that the administration of GH immediately after severe motor cortex injury, in rats, followed by rehabilitation, improved the functionality of the affected limb and reexpressed nestin in the contralateral motor cortex. Here, we analyze whether these GH effects depend on a time window after the injury and on the reexpressi...

Within the theoretical framework of socio-political economics, and more specifically of stakeholder theory, this work examines whether companies operating under different institutional constraints and stakeholder pressure tend to emphasize different models of corporate environmental reporting. Furthermore, the paper tests whether different corporat...

This paper analyzes trace elements concentrations from surface detrital sediments corresponding to 4 rivers located in the artisanal gold mining area of Ponce Enríquez (southern Ecuador) to assess the contamination levels. Moreover, their potential environmental threats were evaluated using both the enrichment factors (EFs) approach and sediment qu...

Background: Cutaneous squamous cell carcinoma (CSCC) is the second most widespread cancer in humans and its incidence is rising. These tumours can evolve as diseases of poor prognosis, and therefore it is important to identify new markers to better predict its clinical evolution. Objectives: We aimed to identify the expression pattern of microRN...

Immigration is not a historical phenomenon associated to population displacements in concrete historical periods but has become a stable phenomenon that begins after the Second World War with the decolonization processes, the economical growth and the necessity of labor force. The increase in immigrant flows and in immigrant population is one of th...

We examine the job situation of women living in rural Salamanca, Spain, using principal coordinates analysis to identify the profile of these women (specifically, those with declared vs. undeclared jobs) and explore what they believe would improve their employment situations. Four well-differentiated groups were identified: two groups included rura...

A new version of MULTBIPLOT as a package for R is under development. The package will be published here before submiting it to CRAN (in small sub projects). The first subproject containing just the biplots for continuous data has been released. The package can be downloaded at: http://biplot.usal.es/classicalbiplot/multbiplot-in-r/

Classical Biplot Methods allow for the simultaneous representation of individuals (rows) and variables (columns) of a data matrix. For Binary data, Logistic biplots have been recently developed.When data are nominal, linear or even binary logistic biplots are not adequate and techniques as Multiple Correspondence Analysis (MCA), Latent Trait Analys...

Classical Biplot methods allow for the simultaneous representation of individuals and variables in a given data matrix. When variables are binary (presence/absence) a classical linear biplot representation is not suitable and logistic biplots have been recently proposed. The coordinates of individuals and variables are computed to have logistic res...

the simultaneous representation of individuals and continuous variables in a given data matrix. When variables are binary, categorical or ordinal, a classical linear biplot representation is not suitable. We propose a linear biplot representation based on logistic response models. The coordinates of individuals and variables are computed to have lo...

The genetic diversity of Venezuelan Caricaceae family collection was studied using 15 random primers of the series OPA, OPK, OPM, OPY, OPO and OPW from Operon Technologies Inc, and the amplification fragments linked with the discrimination among Carica papaya L. and three species of Vasconcellea genera: V. cundinamarcensis Linden, V. cauliflora Jac...

Se estudió la diversidad genética de la colección venezolana de la familia Caricáceas a través de 15 iniciadores aleatorios de las series OPA, OPK, OPM, OPY, OPO y OPW, de Operon Technologies Inc., y se identificaron los fragmentos de amplificación asociados a la discriminación entre Carica papaya L y tres especies del género Vasconcellea: V. cundi...

Correspondence Analysis (CA) is widely used in ecological studies to obtain hypothetical environmental gradients from species abundances. When environmental information is measured, that information is in-cluded in the analysis using Canonical Correspondence Analysis (CCA). If the relationships between species and environment are assumed to be Gaus...

El objetivo de la presente comunicación es poner de manifiesto la importancia de los métodos de representación gráfica multivariante aplicados a las Ciencias de la Documentación, en general, y a las Ciencias de la Documentación Biomédica en particular. El uso de indicadores bibliométricos se ha asumido como una metodología imprescindible para evalu...

El objetivo de esta investigacion fue evaluar la calidad de vida en pacientes clasificados como osteoporoticos en el Ambito de la Atencion primaria. Se llevo a cabo un diseno observacional transversal, los pacientes fueron reclutados de forma consecutiva en un Centro de Salud de Atencion primaria de Salamanca (Espana). Se utilizo un cuestionario so...

There is currently a need to develop tools to identify patients with mild AD and mild cognitive impairment (MCI). We determined the validity and reliability of a brief, easily administered cognitive screening battery consisting of fusion of two well-known brief tests (Mini-Mental Status Examination [MMSE] and Clock Drawing Test [CDT]) (Mini-clock)...

The CHAID (Chi-Squared Automatic Interaction Detection) treebased segmentation technique has been found to be an effective approach for obtaining meaningful segments that are predictive of a K-category (nominal or ordinal) criterion variable. CHAID was designed to detect, in an automatic way, the interaction between several categorical or ordinal p...

The CHAID (Chi-Squared Automatic Interaction Detection) treebased segmentation technique has been found to be an effective approach for obtaining meaningful segments that are predictive of a K-category (nominal or ordinal) criterion variable. CHAID was designed to detect, in an automatic way, the interaction between several categorical or ordinal p...

MULTBIPLOT is a program to perform Biplot Analysis. It contains Classical Biplot, HJ-Biplot, Simple and Multiple Correspondence Analysis for a Contingency Table, Canonical/MANOVA Biplot, Logistic Biplots for Binary Data, Common Biplot for Several groups, among many other biplot techniques. The program tries to implement, in a software tool, the exp...

With the aim of transferring micropropagation techniques to cassava seed producers, a simple and low-cost medium for in vitro micropropagation was developed. CM6740-7 cassava cultivar from CIAT was used as planting material. Commercially available nutrients were used in order to substitute the propagation media components. A Hydro Agri´s fertilizer...

En este trabajo proponemos dos soluciones al problema que se plantea cuando se pretende analizar datos multivariantes, para un conjunto de individuos con estructura de grupos, que además han sido replicados bien sea en ocasiones o en situaciones experimentales diferentes. La primera solución se obtiene aplicando la versión dual del STATIS canónico...

In this work we propose two solutions to the problem we consider when we have multivariate experimental data of individuals with structure of groups that have been repeated at different occasions or experimental situations. We obtain the first solution applying dual version of canonical STATIS proposed by Vallejo-Arboleda et al. (2007), and the sec...

Latent class models (LCMs) can be used to assess diagnostic test performance when no reference test (a gold standard) is available, considering two latent classes representing disease or non-disease status. One of the basic assumptions in such models is that of local or conditional independence: all indicator variables (tests) are statistically ind...

The three-mode Principal Component Analysis (TUCKALS3 model) is used to study three-way structured data, specifically three-order interaction associated to a lineal model. The three-order interaction residuals are decomposed by means of multiplying three marker matrices associated to each source of variation analyzed, searching for the best reduced...

We propose elliptical confidence regions for the Manova-Biplot, instead of the traditionally used confidence circles. These regions are constructed taken into account the sample variability of the representation axes and are based on the mathematical development used by Krzanowski (1989). An application of the theoretical results to a data set, sho...

La marchitez por Fusarium constituye una de las enfermedades más destructivas en Musa, siendo causada por el hongo del suelo Fusarium oxysporum f. sp. cubense. No se cuenta con control químico disponible, siendo la única medida posible la utilización de genotipos resistentes/tolerantes al patógeno. El desarrollo de las técnicas moleculares ha permi...

En este trabajo se presentan los resultados de un estudio, el primero de estas características a nivel de la Comunidad de Castilla y León, cuyo objetivo es identificar los perfiles socioeconómicos de las mujeres salmantinas, en situación de irregularidad laboral, en comparación con las características de las mujeres que desarrollan su actividad en...

Cassava (Manihot esculenta Crantz), is an important root crop in most tropical countries. It is a starchy staple crop for millions of people in the tropics and usually cultivated in marginal environments, mostly by small farmers. Recent progress has been made in the application of molecular genetic diversity analysis for cassava breeding and in the...

Frequently multivariate experimental data taken over multiple occasions is found to produce a multivariate multi-table experiment. Neither the separate analysis of each occasion, using MANOVA or canonical variate analysis, nor the joint analysis using the STATIS- ACT methodology for multiple tables, are adequate to capture the real structure of the...

Debido a los avances tecnol�ogicos la cantidad de informaci�on que se obtiene tras un dise~no experimental es cada vez mayor. En este contexto, los m�etodos multivariantes permiten la reducci�on de la dimensi�on, aprovechan las interrelaciones entre variables, y simpli�can la interpretaci�on. As��, en un MANOVA buscamos las combinaciones lineales d...

Este Libro de Actas recoge los resumenes de los trabajos presentados, en Junio de 2007, por más de 800 investigadores de todo el mundo. Más de 100 Posters, 22 sesiones de Comunicaciones orales, más de 150 Ponencias, 6 Simposios y 8 Conferencias Plenarias. Las Conferencias plenarias versaron sobre: Inferencia mediante Remuestreo (J.L. Chorro); Tests...

Entre los métodos de análisis multivariante de datos, los Biplot han sido fuente de continuas con-tribuciones a la ciencia desde su origen en 1971. Su objetivo general es la aproximación de una matriz de datos, de tal forma que permita su descripción o modelización a través de mapas geo-métricos construidos como proyecciones de nubes de puntos fila...

An alternative estimation method, herein termed Regression Biplots, is shown to approximate a data matrix biplot fitting bilinear models. The biplots and the Principal Components Regression are similar methods when the variables have a symmetrical role, a normal distribution and a convenient meter is introduced in their space. The advantage offered...

In this work, the canonical biplot (CB) method (Vicente-Villardón, 1992; Gower and Hand, 1996) is used to determine the origin, distribution, conservation and pollution state of the different types of stones used in the construction and restoration of monuments of great historical interest. The stone materials (sandstones) used in the Cathedral of...

The objective of this workshop is to spotlight the very latest research in multivariate data analysis, particularly in non-symmetrical (correspondence) analysis, and to discuss future developments. We aim to bring together theoretical and applied researchers in all areas where the subject is currently used, notably agronomy, genetics, sociology, ps...

Realizado en la Facultad de Economía y Empresa de Salamanca, por 5 profesores del centro, para las asignaturas de Estadística de primer y segundo ciclo universitario. La aplicación Web diseñada presenta material didáctico estadístico para que los alumnos (más de 3000) que cursan alguna de las asignaturas de Estadística ofertadas por el Departamento...

Este trabajo generaliza el Manova-Biplot de modelos lineales generales multivariantes para diseños de dos vías, proponiendo cuatro tipos de Biplot: el Biplot Total, el Biplot de Interacción y los Biplots de Filas y Columnas. Estos Biplots permiten estudiar la separación de grupos, la influencia de las variables, el efecto de la interacción, importa...

One of the most useful techniques to analyse latent structures is exploratory Factor Analysis. When several data matrices, arising from different occasions and/or groups, are obtained, the comparison and integration of the resulting latent spaces is an important task. In this paper we propose a factor model for several groups that includes shared c...

The Manova-Biplot for the Multivariate General Linear Model is generalized for two way Manova, and four Biplot representations are proposed: Total Biplot, Interaction Biplot, and Row and Column Biplots. These Biplots allow group separation, the study of the influence of variables, interaction effects, weight of variables in the interaction, row and...

Esta Conferencia está dedicada a la Estadística en Medio Ambiente y es continuación de las ediciones celebradas en La Plata (Argentina) en 1999 y Cádiz (España) en 2001 sobre este mismo tema. Se trata de un evento en el que colaboran activamente la Universidad de Salamanca, la Universidad de Cádiz y la Universidad Nacional de La Plata. Se trata de...

En esta investigación se propone un método alternativo de estimación máximo verosímil, que permite restringir los ejes sobre una representación Biplot, de manera tal que sean combinacio-nes lineales de variables externas. Aun cuando los métodos Biplot Clásicos de Gabriel (1971), se utilizan generalmente para describir matrices de datos, sin hacer s...

When one has information about a set of individuals on several variables, in different groups or contexts, and multivariate analysis is applied to each group the following questions arise: which groups show a similar response? how do the groups differ? how do the individuals differ in their responses in the di6erent groups? These issues have led us...

La posibilidad de interpretar el biplot de una matriz de datos (individuos por variables) como un modelo bilineal multiplicativo, se utiliza en este trabajo para ajustar los denominados biplots de regresión, analizar la geometría, estimación e interpretación. Para su ajuste se propone formalmente un método de estimación máximo verosímil, alternativ...

Los métodos Biplot, en sus vertientes más clásicas o mediante transformaciones previas de los datos, han sido usados para la diagnosis de modelos que se ajusten a conjunto de datos. De este modo, es posible utilizar estas representaciones en dimensión reducida, pero obtenida mediante modelos lineales generalizados alternados, para obtener una visua...

En el presente trabajo realizaremos un estudio comparativo de las dos familias de métodos más utilizados en la práctica para análisis de datos de tres modos: aquéllos métodos considerados simétricos, basados en el modelo de Tucker (TUCKER, 1966), TUCKALS - 2 y TUCKALS -3 (KROONENBERG & De LEEUW, 1980) y el método PARAFAC/CAMDECOM de CARROLL & CHANG...

Se utiliza el TUCKALS3 como método para el análisis de datos con estructura de tres vías. Es un algorítmo diseñado como alternativa para la obtención de estimadores mínimo cuadráticos en el modelo de TUCKER; ofrece una descomposición de los datos en tres marcadores asociados a cada fuente de variación analizada; permitiendo una representación Biplo...

En el presente trabajo se propone la generalización del Manova Biplot a cualquier Modelo Lineal general Multivariante y se obtiene el Manova Biplot de dos vías como caso particular. Se proponen cuatro representaciones que recogen las diferentes fuentes de variación: El Biplot total, que recoge la variación combinada de todos los efectos, el Biplot...

Se hace una generalización del Análisis de Componentes Principales al caso de datos con estructura de tres vías. Los resultados se presentan mediante un Biplot con efecto multiplicativo en los marcadores columnas. A partir de una representación gráfica conjunta en dimensión reducida podemos detectar la presencia de interacción triple y diagnosticar...

Los métodos biplots clásicos de Gabriel (1971) se utilizan generalmente con propósitos descrip-tivos, sin hacer supuestos sobre distribuciones poblacionales, sin embargo, el biplot de una ma-triz de datos puede interpretarse también como un modelo bilineal multiplicativo (Gollob, 1968). Desde esta ultima perpectiva, en esta investigación se analiza...