Now showing items 1-20 of 29

    • A goodness-of-fit test for the ordered stereotype model 

      Fernández Martínez, Daniel; Liu, Ivy (2016-11-10)
      Article
      Open Access
      This paper presents a new goodness-of-fit test for an ordered stereotype model used for an ordinal response variable. The proposed test is based on the well-known Hosmer–Lemeshow test and its version for the proportional ...
    • A method for ordinal outcomes: The ordered stereotype model 

      Fernández Martínez, Daniel; Liu, Ivy; Costilla, Roy (2019-12)
      Article
      Open Access
      Objective : The collection and use of ordinal variables are common in many psychological and psychiatric studies. Although the models for continuous variables have similarities to those for ordinal variables, there are ...
    • Are environmental pollution and biodiversity levels associated to the spread and mortality of COVID-19? A four-month global analysis 

      Fernández Martínez, Daniel; Giné Vázquez, Iago; Liu, Ivy; Yucel, Recai; Nai Ruscone, Marta; Morena, Marianthi; García Fernández, Víctor Gerardo; Haro, Josep Maria; Pan, William; Tyrovolas, Stefanos (2021-02-15)
      Article
      Restricted access - publisher's policy
      On March 12th, 2020, the WHO declared COVID-19 as a pandemic. The collective impact of environ-mental and ecosystem factors, as well as biodiversity, on the spread of COVID-19 and its mortalityevolution remain empirically ...
    • Assigning scores for ordered categorical responses 

      Fernández Martínez, Daniel; Liu, Ivy; Costilla, Roy; Yongqi Gu, Peter (Taylor & Francis, 2019-10-09)
      Article
      Restricted access - publisher's policy
      Deciding on the best statistical method to apply when the response variable is ordinal is essential because the way the categories are ordered in the data is relevant as it could change the results of the analysis. Although ...
    • Bayesian model-based clustering for longitudinal ordinal data 

      Costilla, Roy; Liu, Ivy; Arnold, Richard; Fernández Martínez, Daniel (2019-09)
      Article
      Open Access
      Traditional cluster analysis methods used in ordinal data, for instance k-means and hierarchical clustering, are mostly heuristic and lack statistical inference tools to compare among competing models. To address this we ...
    • Biclustering models for two-mode ordinal data 

      Matechou, Eleni; Liu, Ivy; Fernández Martínez, Daniel; Farias, Miguel; Gjelsvik, Bergljot (2016-09)
      Article
      Open Access
      The work in this paper introduces finite mixture models that can be used to simultaneously cluster the rows and columns of two-mode ordinal categorical response data, such as those resulting from Likert scale responses. ...
    • Categorising count data into ordinal responses with application to ecological communities 

      Fernández Martínez, Daniel; Pledger, Shirley (2016-06)
      Article
      Open Access
      Count data sets may involve overdispersion from a set of species and underdispersion from another set which would require fitting different models (e.g. a negative binomial model for the overdispersed set and a binomial ...
    • Covid-19: la malinterpretación de los datos de la pandemia daña la confianza del público 

      Saez Zafra, Marc; Figueiras Guzmán, Adolfo; Alustiza, Ainhoa; Fernández Martínez, Daniel; Cobo Valeri, Erik; Gómez Melis, Guadalupe; González Alastrué, José Antonio; Fonseca Casas, Pau; Cortés García, Claudio Ulises (2020-11-04)
      Article
      Open Access
    • Dependencia emocional en mujeres: una revisión de la literatura empírica 

      González Bueso, Vega; Santamaría, Juan José; Merino, Laura; Montero, Elena; Fernández Martínez, Daniel; Ribas, Joan (2018-05-06)
      Article
      Open Access
      Introducción: actualmente existe un debate sobre si la “Dependencia Emocional” constituye un trastorno real, el aumento de las publicaciones sobre este tema en los últimos años parece reflejar el interés por este problema. ...
    • Estimation of spatial sampling effort based on presence-only data over a class of species 

      Fernández Martínez, Daniel; Nakamura Savoy, Miguel (2015-03-10)
      Article
      Restricted access - publisher's policy
      Sampling bias contained in data of biological surveys is very common. Bias is clearly a function of roads, cities, rivers, or other physical features that determines accessibility of collectors, and many data sets of species ...
    • Finite mixture biclustering of discrete type multivariate data 

      Fernández Martínez, Daniel; Arnold, Richard; Pledger, Shirley; Liu, Ivy; Costilla, Roy (2018-05-15)
      Article
      Open Access
      Many of the methods which deal with clustering in matrices of data are based on mathematical techniques such as distance-based algorithms or matrix decomposition and eigenvalues. In general, it is not possible to use ...
    • Generalized estimating equations to estimate the ordered stereotype logit model for panel data 

      Spiess, Martin; Fernández Martínez, Daniel; Nguyen, Thuong; Liu, Ivy (2020-06-30)
      Article
      Open Access
      By modeling the effects of predictor variables as a multiplicative function of regression parameters being invariant over categories, and category-specific scalar effects, the ordered stereotype logit model is a flexible ...
    • Internet Gaming Disorder clustering based on personality traits in adolescents, and its relation with comorbid psychological symptoms 

      González Bueso, Vega; Santamaría, Juan José; Oliveras Puigdellivol, Ignasi; Fernández Martínez, Daniel; Montero, Elena (2020-03-01)
      Article
      Open Access
      In recent years, the evidence regarding Internet Gaming Disorder (IGD) suggests that some personality traits are important risk factors for developing this problem. The heterogeneity involved in problematic online gaming ...
    • Internet Gaming Disorder in adolescents: personality, psychopathology and evaluation of a psychological intervention combined with parent psychoeducation 

      González Bueso, Vega; Santamaría, Juan José; Fernández Martínez, Daniel; Merino, Laura; Montero, Elena; Jiménez Murcia, Susana; del Pino Gutiérrez, Amparo; Ribas, Joan (2018-05-28)
      Article
      Open Access
      Internet Gaming Disorder is an increasingly prevalent disorder, which can have severe consequences in affected young people and in their families. There is an urgent need to improve existing treatment programs; these are ...
    • Introducing spaced mosaic plots 

      Fernández Martínez, Daniel; Arnold, Richard; Pledger, Shirley (2014-09-01)
      External research report
      Open Access
      Recent research has developed a group of likelihood-based finite mixture mod- els for a data matrix with ordinal data, establishing likelihood-based multivari- ate methods which applies fuzzy clustering via finite mixtures ...
    • Joint modeling of survival and longitudinal ordered data using a semiparametric approach 

      Preedalikit, Kemmawadee; Liu, Ivy; Hirose, Yuichi; Sibanda, Nokuthaba; Fernández Martínez, Daniel (2016-07-01)
      Article
      Open Access
      Medical research frequently focuses on the relationship between quality of life (QoL) and survival time of subjects. QoL may be one of the most important factors that could be used to predict survival, making it worth ...
    • Mixture-based clustering for the ordered stereotype model 

      Fernández Martínez, Daniel; Arnold, Richard; Pledger, Shirley (2016-01)
      Article
      Open Access
      Many of the methods which deal with the reduction of dimensionality in matrices of data are based on mathematical techniques such as distance-based algorithms or matrix decomposition and eigenvalues. Recently a group of ...
    • Model selection for mixture-based clustering for ordinal data 

      Fernández Martínez, Daniel; Arnold, Richard (2016-12)
      Article
      Restricted access - publisher's policy
      One of the key questions in the use of mixture models concerns the choice of the number of components most suitable for a given data set. In this paper we investigate answers to this problem in the context of likelihood-based ...
    • Model-based goodness-of-fit tests for the ordered stereotype model 

      Fernández Martínez, Daniel; Liu, Ivy; Arnold, Richard; Nguyen, Thuong; Spiess, Martin (2019-07-30)
      Article
      Restricted access - publisher's policy
      This paper presents two new model-based goodness-of-fit tests for the ordered stereotype model applied to an ordinal response variable. The proposed tests are based on the Lipsitz test, which partitions the subjects into ...