Search results for "Clustering"

Comparison of Internal Clustering Validation Indices for Prototype-Based Clustering

2017

Clustering is an unsupervised machine learning and pattern recognition method. In general, in addition to revealing hidden groups of similar observations and clusters, their number needs to be determined. Internal clustering validation indices estimate this number without any external information. The purpose of this article is to evaluate, empirically, characteristics of a representative set of internal clustering validation indices with many datasets. The prototype-based clustering framework includes multiple, classical and robust, statistical estimates of cluster location so that the overall setting of the paper is novel. General observations on the quality of validation indices and on t…

Clustering techniques for personal photo album management

2009

In this work we propose a novel approach for the automatic representation of pictures achieving at more effective organization of personal photo albums. Images are analyzed and described in multiple representation spaces, namely, faces, background and time of capture. Faces are automatically detected, rectified and represented projecting the face itself in a common low-dimensional eigenspace. Backgrounds are represented with low-level visual features based on RGB histogram and Gabor filter bank. Faces, time and background information of each image in the collection is automatically organized using a mean-shift clustering technique. Given the particular domain of personal photo libraries, wh…

GIS-data related route optimization, hierarchical clustering, location optimization, and kernel density methods are useful for promoting distributed …

2019

Currently, geographic information system (GIS) models are popular for studying location-allocation-related questions concerning bioenergy plants. The aim of this study was to develop a model to investigate optimal locations for two different types of bioenergy plants, for farm and centralized biogas plants, and for wood terminals in rural areas based on minimizing transportation distances. The optimal locations of biogas plants were determined using location optimization tools in R software, and the optimal locations of wood terminals were determined using kernel density tools in ArcGIS. The present case study showed that the utilized GIS tools are useful for bioenergy-related decision-maki…

Spatial Patterns of Regional Income Inequality Then and Now

2018

In this chapter an important element characteristic of territorial inequality is examined: the presence of geographical patterns, that is, the grouping of neighbouring regions into clusters of wealth or poverty. The descriptive evidence provided by the maps is supplemented with spatial autocorrelation statistics to test for the presence of spatial clustering. The analysis aims to identify when exactly the geographical patterns that characterize regional inequality in Spain today took shape. Then some hypotheses as to the causes are established. Finally, the chapter analyses whether the clusters of poor or rich regions continue uninterrupted beyond national borders to include regions of Port…

Das polyglanduläre Autoimmunsyndrom – Lebensqualität und familiäre Beteiligung

2014

Hintergrund und Fragestellung: Fur Patienten mit einem Polyglandularem Autoimmunsyndrom (PGA) und ihre Angehorigen liegen keine Daten zur familiaren Beteiligung und zur Lebensqualitat vor. Daher erfolgte eine Erhebung in einer reprasentativen Gruppe. Patienten und Methoden: Im Rahmen einer prospektiv angelegten und kontrollierten Studie wurden klinische und serologische Untersuchungen an 75 konsekutiv aufgenommenen Patienten mit PGA (mittleres Alter 47,5  ±  15,3 Jahre; 65,3 % Frauen) mit 108 Angehorigen (mittleres Alter 33,13 Jahre  ± 20,08 Jahre; 65,7% Frauen) durchgefuhrt. Drei validierte Messinstrumente (Short Form 36 [SF-36], Hospital Anxiety and Depression Scale [HADS] und Giesener Be…

Footprint Curvature in Spanish Women: Implications for Footwear Fit

2020

The incorrect adjustment of footwear produces alterations in the foot that affect quality of life. The usual measurements for shoe design are lengths, widths and girths, but these measures are insufficient. The foot presents an angle between the forefoot and the rearfoot in the transverse plane, which is associated with foot pronation, hallux valgus and metatarsus adductus. Here, we aimed at identifying the groups formed by the angulations between the forefoot and rearfoot using a sample of footprints from 102 Spanish women. The angle between the forefoot and rearfoot was measured according to the method described by Bunch. A cluster analysis was performed using the K-means algorithm. Footp…

A Measure of Polarization for Tourism: Evidence from Italian Destinations

2011

This paper proposes an index of polarization for tourism which links the axiomatic theory of Esteban and Ray with the classical hierarchical agglomerative clustering techniques. The index is aimed at analyzing the dynamics of the average length of stay across Italian destinations, and more specifically to detect whether the polarization within the set of clusters of places with similar values of the indicator has varied over time.

Penalized regression and clustering in high-dimensional data

The main goal of this Thesis is to describe numerous statistical techniques that deal with high-dimensional genomic data. The Thesis begins with a review of the literature on penalized regression models, with particular attention to least absolute shrinkage and selection operator (LASSO) or L1-penalty methods. L1 logistic/multinomial regression models are used for variable selection and discriminant analysis with a binary/categorical response variable. The Thesis discusses and compares several methods that are commonly utilized in genetics, and introduces new strategies to select markers according to their informative content and to discriminate clusters by offering reduced panels for popul…

Basic Chemometric Tools

2013

Abstract The authentication of protected designation of origin and other protected geographical indications for foods involves the need for a deep knowledge of these kinds of samples and the correct identification of appropriate markers that are suitable to be used for authentication purposes. For this, significance tests must be developed and applied to provide evidence in a fast and accurate way; from this, it seems clear that advances in analytical tools, to obtain data regarding food chemical composition, and chemometric data treatments must be continued to provide to the users powerful identification methodologies. In this sense, the objective must be to differentiate between foods pro…

Is the EUA a new asset class?

2022

The listing of a new asset requires knowledge of its statistical properties prior to its use for hedging, speculative or risk management purposes. In this paper, the authors study the stylised facts of European Union Allowances (EUAs) returns. The majority of the phenomena observed, such as heavy tails, volatility clustering, asymmetric volatility and the presence of a high number of outliers are similar to those observed in both commodity futures and financial assets. However, properties such as negative asymmetry, positive correlation with stocks indexes and higher volatility levels during the trading session, typical of financial assets, and the existence of inflation hedge and positive …