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Ana Belén Ramos-Guajardo

Ana Belén Ramos-Guajardo
University of Oviedo | UNIOVI · Department of Statistics and Operational Research and Mathematics Didactics

PhD in Mathematics

About

36
Publications
3,965
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380
Citations
Citations since 2016
14 Research Items
260 Citations
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2016201720182019202020212022010203040
2016201720182019202020212022010203040
2016201720182019202020212022010203040

Publications

Publications (36)
Article
Some hypothesis tests for analyzing the degree of overlap between the expected value of random intervals are provided. For this purpose, a suitable measure to quantify the overlapping grade between intervals is considered on the basis of the Szymkiewicz-Simpson coefficient defined for general sets. It can be seen as a kind of likeness index to meas...
Conference Paper
Full-text available
Seismic data are typically employed to monitor earthquake activity, but they can also be exploited in order to investigate the existing links betweenthe seismic signal and a broad range of physical processes occurring in the nearby rivers. For instance, the noise related to water turbulence duringhigh discharges has a clear impact on the seismic si...
Article
Most of the distances used in case of fuzzy data are based on the well-known Euclidean distance. In detail, a fuzzy number can be characterized by centers and spreads and the most common distances between fuzzy numbers are essentially defined as a weighted sum of the squared Euclidean distances between the centers and the spreads. In the multivaria...
Article
Full-text available
Some regression models for analyzing relationships between random intervals (i.e., random variables taking intervals as outcomes) are presented. The proposed approaches are extensions of previous existing models and they account for cross relationships between midpoints and spreads (or radii) of the intervals in a unique equation based on the inter...
Chapter
Full-text available
Sensory analysis entails subjective valuations provided by qualified experts which in most of the cases are given by means of a real value. However personal valuations usually present an uncertainty in their meaning which is difficult to capture by using a unique value. In this work some statistical techniques to deal with such kind of information...
Poster
Full-text available
Coastal sand dune ecosystems are facing threats and pressures across Europe, but the quantification of the exact impacts is not easy, particularly when natural and anthropic effects are overlapping. In order to tackle this question, during two years sand movement has been measured in pilot dune plots located in the Northern Spanish coast. We aimed...
Chapter
Full-text available
The convenient theoretical properties of the support function and the Minkowski addition-based arithmetic have been shown to be useful when dealing with compact and convex sets on Rp. However, both concepts present several drawbacks in certain contexts. The use of the radial function instead of the support function is suggested as an alternative to...
Article
Full-text available
The space of nonempty convex and compact (fuzzy) subsets of Rp, Kc(Rp), has been traditionally used to handle imprecise data. Its elements can be characterized via the support function, which agrees with the usual Minkowski addition, and naturally embeds Kc(Rp) into a cone of a separable Hilbert space. The support function embedding holds interesti...
Chapter
Full-text available
Classical tests for the equality of distributions of real-valued random variables are widely applied in Statistics. When the normality assumption for the variables fails, non-parametric techniques are to be considered; Mann-Whitney, Wilcoxon, Kruskal-Wallis, Friedman tests, among other alternatives. Fuzzy representations of real-valued random varia...
Chapter
Full-text available
The similarity degree between the expectation of two random intervals is studied by means of a hypothesis testing procedure. For this purpose, a similarity measure for intervals is introduced based on the so-called Jaccard index for convex sets. The measure ranges from 0 (if both intervals are not similar at all, i.e., if they are not overlapped) t...
Article
Full-text available
Interval-valued observations arise in many real-life situations as either the precise representation of the objective entity or the representation of incomplete knowledge. Thus given p features observed over a sample of objects belonging to one of two possible classes, each observation can be perceived as a non-empty closed and bounded hyperrectang...
Article
Full-text available
Spanish primary and secondary school curricula comprise several contents, learning outcomes and assessment criteria directly related with probability and approximate calculus. Some of them refer to situations modeled by the students, which entail not only uncertainty but also imprecision. For this reason, different techniques including fuzzy logic...
Article
Full-text available
A fuzzy clustering method for random fuzzy sets is proposed. The starting point is a p-value matrix with elements obtained by comparing the expected values of random fuzzy sets by means of a bootstrap test. As such, the p-value matrix can be viewed as a relational data matrix since the p-values represent a kind of similarity between random fuzzy se...
Article
Full-text available
A hypothesis test for analyzing the degree of similarity between the expected value of a random interval and a fixed interval is introduced. It is based on a measure of the similarity between classical convex sets proposed in the literature. Asymptotic techniques are firstly applied to analyze the limit distribution of the proposed test statistic....
Conference Paper
Full-text available
The reliability of the fuzzy scale for assessing the responses of a person in an opinion questionnaire (which is usually treated as a Likert-type questionnaire) is analyzed. Thus, a comparison between a classical Likert scale-based questionnaire and its fuzzy rating scale-based version in terms of their reliability is established. For this purpose,...
Conference Paper
Full-text available
A novel way for addressing one-sided hypothesis tests for the mean of unable to observe real random variables from which we have information provided in terms of interval data is proposed. For this purpose, a measure of similarity between intervals is considered and the classical one-sided hypothesis test to check whether the similarity between the...
Article
An extension of the inclusion test of the expected value of a real random variable in an interval to the case of general random intervals is introduced. The hypothesis of strict inclusion is relaxed by considering a measure of the degree of inclusion. Thus, partial inclusions are also tested. Asymptotic and bootstrap techniques are established. The...
Article
Full-text available
Real-life data associated with experimental outcomes are not always real-valued. In particular, opinions, perceptions, ratings, etc. are often assumed to be imprecise in nature, especially when they come from human valuations. Fuzzy numbers have long been considered to provide us with a convenient scale to express these imprecise data. In analyzing...
Article
Full-text available
This note is a rejoinder on our paper in this issue. It attempts to provide some clarifications and thoughts in connection with the discussions/comments made about it by Didier Dubois and Sebastien Destercke. We hope our comments are at the level of the discussants'.
Article
A hypothesis test for the inclusion of the expected value of a fuzzy-valued random element in a given fuzzy set is provided. The exclusion, or the empty intersection of the expected value of a random fuzzy set and a fuzzy set, is also tested, that allows us to define one-sided tests for this expected value without the need of considering any restri...
Article
Full-text available
The so-called fuzzy representations of real-valued random variables are reviewed. They are used to visualize or/and characterize distributions through fuzzy sets. Various fuzzy representations useful to explore or test about different characteristics of real distributions are described. The main developments concerning the representation, goodness-...
Article
Full-text available
Data obtained in association with many real-life random experiments from different fields cannot be perfectly/exactly quantified. Often the underlying imprecision can be suitably described in terms of fuzzy numbers/ values. For these random experiments, the scale of fuzzy numbers/values enables to capture more variability and subjectivity than that...
Chapter
Full-text available
Most of the research developed in the last years by the SMIRE Research Group concerns the statistical analysis of imprecisely (set- and fuzzy set)-valued experimental data. This analysis has been based on an approach considering the usual arithmetic for these data as well as suitable metrics between them. The research perfectly fits into the resear...
Article
A methodology for analyzing the variability of the tidal fluctuation in a specific area is proposed in this work. The idea is to consider intervals determined by the minimum and maximum height reached by the tides in a day. Thus, the theoretical aim is to develop hypothesis tests about the variance of one or more interval-valued random elements (i....
Chapter
Full-text available
The problem of testing the equality of variances of k random fuzzy sets has been recently developed on the basis of Levene's classical procedure. Asymptotic and bootstrap approaches have been carried out in this framework, and the proposed test was compared with a Bartlett-type test. In this work, a deeper comparison between some bootstrap statisti...
Article
Full-text available
The problem of testing equality of variances often arises when distributions of random variables are compared or linear models between them are considered. The usual tests for variances given normality of the underlying populations are highly non-robust to non-normality and are strongly dependent on the kurtosis. Some alternative formulations of Le...
Article
Full-text available
A methodology for analyzing the quality of a specific kind of cheese is proposed in this work. The idea consists in extending the well-known categorical scale corresponding to the possible perceptions of qualified experts (that commonly ranges from “very bad quality” to “very high quality”) to a more flexible scale. In addition, some statistical in...
Article
En muchas ocasiones en el resultado de un experimento aleatorio subyace algún tipo de imprecisión que puede tratarse considerando intervalos o conjuntos difusos. Los datos difusos generalizan los datos de conjunto y de intervalo y a su vez constituyen una clase particular de datos funcionales lo que permite una mayor operatividad en el ámbito estad...
Article
Full-text available
A procedure to test hypotheses about the population variance of a fuzzy random variable is analyzed. The procedure is based on the theory of UH-statistics. The variance is defined in terms of a general metric to quantify the variability of the fuzzy values about its (fuzzy) mean. An asymptotic one-sample test in a wide setting is developed and a bo...
Article
Some tools for testing hypotheses about the variance of random fuzzy sets are already available. Asymptotically correct procedures for the k-sample homoscedasticity tests have been recently developed. However, the power of such procedures has not been analyzed yet. In this paper, some studies about the power function of the asymptotic procedure for...
Chapter
Full-text available
In this communication we present a procedure to test whether the variance of a fuzzy random variable (FRV) is a given value or not by using asymptotic techniques. The variance considered here is defined in terms of a generalized metric in order to quantify the variability of the fuzzy values of the FRV about its expected value. We present some simu...
Conference Paper
Full-text available
In previous works valuable tools in testing statistical hypotheses about the means of fuzzy random variables have been developed. In this paper we present a study about the power function of an asymptotic procedure for the one-sample test. More precisely, the behaviour of the statistic under local alternatives is analyzed. The procedure is carried...

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