3 research outputs found
Comparison of Positivity in Two EpidemicWaves of COVID-19 in Colombia with FDA
We use the functional data methodology to examine whether there are significant differences
between two waves of contagion by COVID-19 in Colombia between 7 July 2020 and 20 July 2021.
A pointwise functional t-test is initially used, then an alternative statistical test proposal for paired
samples is presented, which has a theoretical distribution and performs well in small samples. Our
statistical test generates a scalar p-value, which provides a global idea about the significance of the
positivity curves, complementing the existing punctual tests, as an advantage.Government of Andalusia (Spain) PID2020-113961GB-I00Ministry of Science and Innovation, Spain (MICINN)
Spanish GovernmentEuropean Commission CEX2020-001105-M/AEI/10.13039/501100011033.Junta de Andaluci
Scalar Variance and Scalar Correlation for Functional Data
In Functional Data Analysis (FDA), the existing summary statistics so far are elements in
the Hilbert space L2 of square-integrable functions. These elements do not constitute an ordered
set; therefore, they are not sufficient to solve problems related to comparability such as obtaining
a correlation measurement or comparing the variability between two sets of curves, determining
the efficiency and consistency of a functional estimator, among other things. Consequently, we
present an approach of coherent redefinition of some common summary statistics such as sample
variance, sample covariance and correlation in Functional Data Analysis (FDA). Regarding variance,
covariance and correlation between functional data, our summary statistics lead to numbers instead
of functions which is helpful for solving the aforementioned problems. Furthermore, we briefly
discuss the functional forms coherence of some statistics already present in the FDA. We formally
enumerate and demonstrate some properties of our functional summary statistics. Then, a simulation
study is presented briefly, with evidence of the consistency of the proposed variance. Finally, we
present the implementation of our statistics through two application examples.Government of Andalucia (Spain) FQM-307Junta de Andalucia A-FQM-66-UGR20European Commissio
Acerca de la estimaci贸n de la fracci贸n PM2.5/PM10
Se discute la estimaci贸n de la fracci贸n PM2.5/PM10, que algunos autores reportan como la raz贸n PM2.5/PM10. Estudios previos destacan la importancia de esta fracci贸n en el estudio del impacto de las part铆culas en el aire sobre la salud de las personas y su uso potencial en la reconstrucci贸n y en la imputaci贸n de datos de los niveles de part铆culas finas PM2.5 a partir de los niveles de part铆culas gruesas PM10. Se sugiere adaptar la estimaci贸n, mediante el uso de diferentes estrategias para situaciones particulares, incluyendo el modelo lineal general (GLM), la regresi贸n a trav茅s del origen (RTO), los modelos aditivos generalizados (GAM) y los modelos de regresi贸n usando m铆nimos cuadrados ponderados (WLS)