SORT : Statistics and Operations Research Transactions
SORT (ISSN 1696-2281 / ISSN electrònic 2013-8830) is an international biannual publication jointly published by Idescat and fours catalan universities (Universitat Politècnica de Catalunya, Universitat de Barcelona, Universitat Autònoma de Barcelona i Universitat de Girona) and with the collaboration of Regió Espanyola de la Societat Internacional de Biometria. Fully published in English (with abstracts in Catalan) promotes the publication of original articles on statistical methodology and applied statistics, operations research, official statistics and biometrics, as well as reviews of books and other publications in this field. SORT is published since 2003 and represents the third part of Qüestió (Quaderns d'Estadística i Investigació Operativa), published by Idescat since 1992.
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2019-01-08
07:42
16 p, 542.3 KB Poisson excess relative risk models : new implementations and software / Higueras, Manuel (Universidad de La Rioja. Departamento de Matemáticas y Computación) ; Howes, Adam (Basque Center for Applied Mathematics - BCAM)
Two new implementations for fitting Poisson excess relative risk methods are proposed for assumed simple models. This allows for estimation of the excess relative risk associated with a unique exposure, where the background risk is modelled by a unique categorical variable, for example gender or attained age levels. [...]
2018 - 10.2436/20.8080.02.76
SORT : statistics and operations research transactions, Vol. 42 Núm. 2 (July-December 2018) , p. 237-252 (Articles)  
2019-01-08
07:42
28 p, 2.9 MB Effect of agro-climatic conditions on near infrared spectra of extra virgin olive oils / Sánchez Rodríguez, María Isabel (Universidad de Córdoba. Departamento de Estadística, Econometría) ; Sánchez López, Elena M. (Universidad de Córdoba. Departamento de Química Orgánica) ; Caridad, José Mª (Universidad de Córdoba. Departamento de Estadística, Econometría) ; Marinas, Alberto (Universidad de Córdoba. Departamento de Química Orgánica) ; Urbano, Francisco José (Universidad de Córdoba. Departamento de Química Orgánica)
Authentication of extra virgin olive oil requires fast and cost-effective analytical procedures, such as near infrared spectroscopy. Multivariate analysis and chemometrics have been successfully applied in several papers to gather qualitative and quantitative information of extra virgin olive oils from near infrared spectra. [...]
2018 - 10.2436/20.8080.02.75
SORT : statistics and operations research transactions, Vol. 42 Núm. 2 (July-December 2018) , p. 209-236 (Articles)  
2019-01-08
07:42
24 p, 3.7 MB Field rules and bias in random surveys with quota samples : an assessment of CIS surveys / Pavía, Jose M. (Universitat de València. Departament de Matemàtica Aplicada) ; Aybar, Cristina (Universitat de València. Departament de Matemàtica Aplicada)
Surveys applying quota sampling in their final step are widely used in opinion and market research all over the world. This is also the case in Spain, where the surveys carried out by CIS (a public institution for sociological research supported by the government) have become a point of reference. [...]
2018 - 10.2436/20.8080.02.74
SORT : statistics and operations research transactions, Vol. 42 Núm. 2 (July-December 2018) , p. 183-206 (Articles)  
2019-01-08
07:42
24 p, 517.9 KB Efficiency of propensity score adjustment and calibration on the estimation from non-probabilistic online surveys / Ferri-García, Ramón (Universidad de Granada. Departamento de Estadística) ; Rueda, Maria del Mar (Universidad de Granada. Departamento de Estadística)
One of the main sources of inaccuracy in modern survey techniques, such as online and smartphone surveys, is the absence of an adequate sampling frame that could provide a probabilistic sampling. This kind of data collection leads to the presence of high amounts of bias in final estimates of the survey, specially if the estimated variables (also known as target variables) have some influence on the decision of the respondent to participate in the survey. [...]
2018 - 10.2436/20.8080.02.73
SORT : statistics and operations research transactions, Vol. 42 Núm. 2 (July-December 2018) , p. 159-182 (Articles)  
2019-01-08
07:42
34 p, 520.2 KB A contingency table approach based on nearest neighbour relations for testing self and mixed correspondence / Ceyhan, Elvan (North Carolina State University. Department of Statistics)
Nearest neighbour methods are employed for drawing inferences about spatial patterns of points from two or more classes. We introduce a new pattern called correspondence which is motivated by (spatial) niche/habitat specificity and segregation, and define an associated contingency table called a correspondence contingency table, and examine the relation of correspondence with the motivating patterns (namely, segregation and niche specificity). [...]
2018 - 10.2436/20.8080.02.72
SORT : statistics and operations research transactions, Vol. 42 Núm. 2 (July-December 2018) , p. 125-158 (Articles)  
2019-01-08
07:42
24 p, 432.6 KB Evidence functions : a compositional approach to information / Egozcue, Juan-José (Universitat Politècnica de Catalunya. Departament d'Enginyeria Civil i Ambiental) ; Pawlowsky-Glahn, Vera (Universitat de Girona. Departament d'Informàtica i Matemàtica Aplicada)
The discrete case of Bayes’ formula is considered the paradigm of information acquisition. Prior and posterior probability functions, as well as likelihood functions, called evidence functions, are compositions following the Aitchison geometry of the simplex, and have thus vector character. [...]
2018 - 10.2436/20.8080.02.71
SORT : statistics and operations research transactions, Vol. 42 Núm. 2 (July-December 2018) , p. 101-124 (Invited articles)  
2018-06-26
05:06
26 p, 426.3 KB Empirical analysis of daily cash flow time-series and its implications for forecasting / Salas-Molina, Francisco (Universitat de València) ; Rodríguez Aguilar, Juan Antonio (Institut d'Investigació en Intel·ligència Artificial (IIIA-CSIC)) ; Serra Sagristà, Joan (Telefónica Research (Barcelona, Catalunya)) ; Guillén, Montserrat (Universitat de Barcelona. Departament d'Econometria) ; Martin, Francisco J. (BigML, Inc. (Corvallis, Estats Units d'Amèrica))
Usual assumptions on the statistical properties of daily net cash flows include normality, absence of correlation and stationarity. We provide a comprehensive study based on a real-world cash flow data set showing that: (i) the usual assumption of normality, absence of correlation and stationarity hardly appear; (ii) non-linearity is often relevant for forecasting; and (iii) typical data transformations have little impact on linearity and normality. [...]
2018 - 10.2436/20.8080.02.70
SORT : statistics and operations research transactions, Vol. 42 Núm. 1 (January-June 2018) , p. 73-98 (Articles)  
2018-06-26
05:06
14 p, 370.8 KB Heteroscedasticity irrelevance when testing means difference / Flores M., Pablo (Escuela Superior Politécnica de Chimborazo (Equador). Grupo de Investigación en Ciencia de Datos CIDED) ; Ocaña, Jordi (Universitat de Barcelona)
Heteroscedasticity produces a lack of type I error control in Student’s t test for difference between means. Pretesting for it (e. g. , by means of Levene’s test) should be avoided as this also induces type I error. [...]
2018 - 10.2436/20.8080.02.69
SORT : statistics and operations research transactions, Vol. 42 Núm. 1 (January-June 2018) , p. 59-72 (Articles)  
2018-06-26
05:06
24 p, 434.0 KB Using a Bayesian change-point statistical model with autoregressive terms to study the monthly number of dispensed asthma medications by public health services / Mota de Queiroz, J. A. (Instituto Federal do Paraná – IFPR (Brasil)) ; Aragon, Davi Casale (Universidade de São Paulo. Ribeirão Preto Medical School) ; Mello, Luane Marques de (Universidade de São Paulo. Ribeirão Preto Medical School) ; Previdelli, Isolde Terezinha Santos (Universidade Estadual de Maringá) ; Martinez, Edson Z. (Universidade de São Paulo. Ribeirão Preto Medical School)
In this paper, it is proposed a Bayesian analysis of a time series in the presence of a random change-point and autoregressive terms. The development of this model was motivated by a data set related to the monthly number of asthma medications dispensed by the public health services of Ribeirao Preto, Southeast Brazil, from 1999 to 2011. [...]
2018 - 10.2436/20.8080.02.66
SORT : statistics and operations research transactions, Vol. 42 Núm. 1 (January-June 2018) , p. 3-26 (Articles)  
2018-06-26
05:06
18 p, 517.3 KB Evaluating the complexity of some families of functional data / Bongiorno, Enea G. (Università del Piemonte Orientale) ; Goia, Aldo (Università del Piemonte Orientale) ; Vieu, Philippe (Université Paul Sabatier. Institut de Mathématiques de Toulouse)
In this paper we study the complexity of a functional data set drawn from particular processes by means of a two-step approach. The first step considers a new graphical tool for assessing to which family the data belong: the main aim is to detect whether a sample comes from a monomial or an exponential family. [...]
2018 - 10.2436/20.8080.02.67
SORT : statistics and operations research transactions, Vol. 42 Núm. 1 (January-June 2018) , p. 27-44 (Articles)