arXiv subjects

Rosa M. Crujeiras

Publications and source records attributed to Rosa M. Crujeiras.

23 records · Page 2Linked to original sources

arXiv2020

Nonparametric multivariate regression estimation for circular responses

Nonparametric estimators of a regression function with circular response and Rd-valued predictor are considered in this work. Local polynomial type 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 finite sample behavior of the proposed estimators is assessed through simulations and their performance is also illustrated with a real data set.

stat.ME↗

arXiv2019

Mode testing, critical bandwidth and 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 excess mass. However, none of the existing proposals provides a satisfactory performance in practice. In this work, a new procedure which combines the previous approaches (smoothing and excess mass) is presented and compared with the existing methods, showing a superior behaviour. A real data example on philatelic data is also included for illustration purposes.

stat.ME↗

arXiv2018

Fire seasonality identification with multimodality tests

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 interest to analyze where human activity has influenced the fire seasonality. For doing so, multimodality tests are a useful tool for determining the number of fire peaks along the year. The periodicity of climatological and human--altered fires and their complex distributional features motivate the use of the nonparametric circular statistics. The unsatisfactory performance of previous nonparametric proposals for testing multimodality, in the circular case, justifies the introduction of a new approach, accompanied by a correction of the False Discovery Rate with spatial dependence for a systematic application of the tests in a large area between Russia and Kazakhstan.

stat.AP↗

arXiv2018

Multimode: An R Package for Mode Assessment

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 and their estimated location. Specifically, some graphical tools, allowing for the identification of mode patterns, based on the kernel density estimation are provided (SiZer map, mode tree or mode forest). Several formal testing procedures for determining the number of modes are described in this paper and implemented in the multimode package, including methods based on the ideas of the critical bandwidth, the excess mass or using a combination of both. This package also includes a function for estimating the modes locations and different classical data examples that have been considered in mode testing literature.

stat.CO↗

arXiv2013

CircSiZer: an exploratory tool for circular data

Smoothing methods and SiZer (SIgnificant ZERo crossing of the derivatives) are useful tools for exploring significant underlying structures in data samples. An extension of SiZer to circular data, namely CircSiZer, is introduced. Based on scale-space ideas, CircSiZer presents a graphical device to assess which observed features are statistically significant, both for density and regression analysis with circular data. The method is intended for analyzing the behavior of wind direction in the atlantic coast of Galicia (NW Spain) and how it has an influence over wind speed. The performance of CircSiZer is also checked with some simulated examples.

stat.AP↗