Cluster analysis exploratory data

Other methods consist of algorithms based on multivariate classification techniques or neural networks they are constructed for automatic recognition of structural properties from spectral data, or for simulation of spectra from structural properties [83]. Multivariate data analysis for spectrum interpretation is based on the characterization of spectra by a set of spectral features. A spectrum can be considered as a point in a multidimensional space with the coordinates defined by spectral features. Exploratory data analysis and cluster analysis are used to investigate the multidimensional space and to evaluate rules to distinguish structure classes. 

Spectral features and their corresponding molecular descriptors are then applied to mathematical techniques of multivariate data analysis, such as principal component analysis (PCA) for exploratory data analysis or multivariate classification for the development of spectral classifiers [84-87]. Principal component analysis results in a scatter plot that exhibits spectra-structure relationships by clustering similarities in spectral and/or structural features [88, 89]. 

Exploratory data analysis has the aim to learn about the data distribution (clusters, groups of similar objects). In multivariate data analysis, an X-matrix (objects/samples characterized by a set of variables/measurements) is considered. Most used method for this purpose is PCA, which uses latent variables with maximum variance of the scores (Chapter 3). Another approach is cluster analysis (Chapter 6). 

Cluster analysis will be discussed in Chapter 6 in detail. Here we introduce cluster analysis as an alternative nonlinear mapping technique for exploratory data analysis. The method allows gaining more insight into the relations between the objects if a... 

Unsupervised pattern recognition differs from exploratory data analysis in diat the aim of the methods is to detect similarities, whereas using EDA diere is no particular prejudice as to whether or how many groups will be found. Cluster analysis is described in more detail in Section 4.4. 

A special case of exploratory data analysis aimed at grouping similar objects in the same cluster and less similar objects in different clusters [Massart and Kaufman, 1983 Willett, 1987], Cluster analysis is based on the evaluation of the -> similarity/diversity of all the pairs of objects of a data set. This information is collected into the - similarity matrix or - data distance matrix. 

Exploratory data analysis is a collection of techniques that search for structure in a data set before calculating any statistic model [Krzanowski, 1988]. Its purpose is to obtain information about the data distribution, about the presence of outliers and clusters, and to disclose relationships and correlations between objects and/or variables. Principal component analysis and cluster analysis are the most well-known techniques for data exploration [Jolliffe, 1986 Jackson, 1991 Basilevsky, 1994]. 

Exploratory modeling using modem statistical modeling techniques such as generalized additive modeling (GAM) (15), cluster analysis, and tree-based modehng (TBM) to reveal structure in the data and initially select explanatory covariates. 

Data sets can be analyzed by exploratory data analysis, usually based on multivariate techniques, such as principal component analysis cluster analysis allows the evaluation of... 

Exploratory data analysis is a common preliminary step in all the QSAR/QSPR studies. In particular. Principal Component Analysis (PCA) and clustering methods... 

In the first mentioned type of application, electrophoretic data are subjected to exploratory analysis techniques, such as principal component analysis (PCA) (5-8), robust PCA (rPCA) (9-13), projection pursuit (PP) (6,14-18), or cluster analysis (8, 19, 20). They all result in a simple low-dimensional visualization of the multivariate data. As a consequence, it will be easier for the analyst to get insight in the data in order to see whether there is a given... 

A whole spectrum of statistical techniques have been applied to the analysis of DNA microarray data [26-28]. These include clustering analysis (hierarchical, K-means, self-organizing maps), dimension reduction (singular value decomposition, principal component analysis, multidimensional scaling, or correspondence analysis), and supervised classification (support vector machines, artificial neural networks, discriminant methods, or between-group analysis) methods. More recently, a number of Bayesian and other probabilistic approaches have been employed in the analysis of DNA microarray data [11], Generally, the first phase of microarray data analysis is exploratory data analysis. 

Cluster analysis is justifiably a popular and common technique for exploratory data analysis. Most commercial multivariate statistical software packages offer several algorithms, along with a wide range of graphical display facilities to aid the user in identifying patterns in data. Having indicated that... 

Cluster analysis is an exploratory data analysis tool for solving classification problems of contaminants and identifying their original sources. Its object is to sort cases (various organic contaminants) into groups or clusters (ahphatics. 

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