Search results for "Statistica"
showing 10 items of 5969 documents
CHOOSING OF OPTIMAL REFERENCE SAMPLES FOR BOREAL LAKE CHLOROPHYLL A CONCENTRATION MODELING USING AERIAL HYPERSPECTRAL DATA
2018
Abstract. Optical remote sensing has potential to overcome the limitations of point estimations of lake water quality by providing spatial and temporal information. In open ocean waters the optical properties are dominated by phytoplankton density, while the relationship between color and the constituents is more complicated in inland waters varying regionally and seasonally. Concerning the difficulties relating to comprehensive modeling of complex inland and coastal waters, the alternative approach is considered in this paper: the raw digital numbers (DN) recorded using aerial remote hyperspectral sensing are used without corrections and derived by means of regression modeling to predict C…
CLUSTERING INCOMPLETE SPECTRAL DATA WITH ROBUST METHODS
2018
Abstract. Missing value imputation is a common approach for preprocessing incomplete data sets. In case of data clustering, imputation methods may cause unexpected bias because they may change the underlying structure of the data. In order to avoid prior imputation of missing values the computational operations must be projected on the available data values. In this paper, we apply a robust nan-K-spatmed algorithm to the clustering problem on hyperspectral image data. Robust statistics, such as multivariate medians, are more insensitive to outliers than classical statistics relying on the Gaussian assumptions. They are, however, computationally more intractable due to the lack of closed-for…
DIF in the Spanish Version of the Verbal Selective Reminding Test Using Samples From Hispanics in the United States, Mexicans, and Spaniards
2019
Before a test can be used in the target population, it is necessary to demonstrate that there is measurement equivalence. One way to do this is by studying differential item functioning. Objective: In this study, we used the Mantel-Haenszel procedure and logistic regression to analyze DIF in the Spanish version of the Verbal Selective Reminding Test between Spaniards, Mexicans and Hispanics in the United States. Method: Three balanced samples, matched by age, education and sex, were studied: Spaniards, Mexicans and Hispanics (616 healthy participants from Spain (n = 211), Mexico (n = 201) and the United States (n = 205). A six-trial version of the Spanish version of the Verbal Selective Rem…
Comparative Analysis of Spatial Interpolation Methods in the Mediterranean Area: Application to Temperature in Sicily
2015
An exhaustive comparison among different spatial interpolation algorithms was carried out in order to derive annual and monthly air temperature maps for Sicily (Italy). Deterministic, data-driven and geostatistics algorithms were used, in some cases adding the elevation information and other physiographic variables to improve the performance of interpolation techniques and the reconstruction of the air temperature field. The dataset is given by air temperature data coming from 84 stations spread around the island of Sicily. The interpolation algorithms were optimized by using a subset of the available dataset, while the remaining subset was used to validate the results in terms of the accur…
High Performance 3D PET Reconstruction Using Spherical Basis Functions on a Polar Grid
2011
Statistical iterative methods are a widely used method of image reconstruction in emission tomography. Traditionally, the image space is modelled as a combination of cubic voxels as a matter of simplicity. After reconstruction, images are routinely filtered to reduce statistical noise at the cost of spatial resolution degradation. An alternative to produce lower noise during reconstruction is to model the image space with spherical basis functions. These basis functions overlap in space producing a significantly large number of non-zero elements in the system response matrix (SRM) to store, which additionally leads to long reconstruction times. These two problems are partly overcome by expl…
All-Possible-Couplings Approach to Measuring Probabilistic Context.
2013
From behavioral sciences to biology to quantum mechanics, one encounters situations where (i) a system outputs several random variables in response to several inputs, (ii) for each of these responses only some of the inputs may "directly" influence them, but (iii) other inputs provide a "context" for this response by influencing its probabilistic relations to other responses. These contextual influences are very different, say, in classical kinetic theory and in the entanglement paradigm of quantum mechanics, which are traditionally interpreted as representing different forms of physical determinism. One can mathematically construct systems with other types of contextuality, whether or not …
Challenges in dental statistics: data and modelling
2022
The aim of this work is to present the reflections and proposals derived from the first Workshop of the SISMEC STATDENT working group on statistical methods and applications in dentistry, held in Ancona (Italy) on 28th September 2011. STATDENT began as a forum of comparison and discussion for statisticians working in the field of dental research in order to suggest new and improve existing biostatistical and clinical epidemiological methods. During the meeting, we dealt with very important topics of statistical methodology for the analysis of dental data, covering the analysis of hierarchically structured and over-dispersed data, the issue of calibration and reproducibility, as well as some…
Challenges in dental statistics: survey methodology topics
2022

 This paper gathers some contributions concerning survey methodology in dental research, as discussed during the first Workshop of the SISMEC STATDENT working group on statistical methods and applications in dentistry, held in Ancona on the 28th September 2011.
 The first contribution deals with the European Global Oral Health Indicators Development (EGOHID) Project which proposed a comprehensive and standardized system of epidemiological tools (questionnaires and clinical forms) for national data collection on oral health in Europe. The second contribution regards the design and conduct of trials to evaluate the clinical efficacy and safety of toothbrushes and mouthrinses. Final…
El afrontamiento del diagnóstico en pacientes y familiares oncológicos
2016
Introducción: La enfermedad oncológica produce un gran impacto emocional en nuestra población, no solo a los pacientes que las sufren sino a todo el entorno. Conocer el grado de afectación de la enfermedad tanto para los pacientes como a los familiares es primordial para el correcto cuidado por el personal sanitario. Pudiendo mejorar el afrontamiento de la enfermedad. Por tanto el presente estudio pretende conocer el grado de afectación del diagnóstico oncológico en pacientes como en familiares, así como conocer los aspectos que favorezcan el mismo.Metodología: Estudio descriptivo, observacional, transversal llevado a cabo en el Consorcio Hospitalario Provincial de Castellón, en 50 paciente…
Why do female and male taekwondo athletes win the bout? An analysis based on the Olympic weight category and the result of the bout
2020
Combat sports such as taekwondo, where athletes compete against an opponent require control of technique and tactics, as well as knowing the optimal performance of opponents to win the bout. Therefore, the aim of the present study was to analyse the Olympic competitors (London Olympic Games), according to the weight category (fly, feather, light and heavy) and according to the performance in their fighting (winner vs. loser) in each gender. An observational methodology was used, following a nomothetic, follow-up and multidimensional design of 302 individual performances. The statistical analysis used an ANOVA and T Student test for comparing frequencies. The results obtained indicate signif…