Journal ArticleDOI
Variable selection in large environmental data sets using principal components analysis
TLDR
In this article, four methods of variable selection along with different criteria levels for deciding on the number of variables to retain were examined along with a selection method that requires one principal component analysis and retains variables by starting with selection from the first component.Abstract:
In many large environmental datasets redundant variables can be discarded without the loss of extra variation. Principal components analysis can be used to select those variables that contain the most information. Using an environmental dataset consisting of 36 meteorological variables spanning 37 years, four methods of variable selection are examined along with different criteria levels for deciding on the number of variables to retain. Procrustes analysis, a measure of similarity and bivariate plots are used to assess the success of the alternative variable selection methods and criteria levels in extracting representative variables. The Broken-stick model is a consistent approach to choosing significant principal components and is chosen here as the more suitable criterion in combination with a selection method that requires one principal component analysis and retains variables by starting with selection from the first component. Copyright © 1999 John Wiley & Sons, Ltd.read more
Citations
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Giving meaningful interpretation to ordination axes: assessing loading significance in principal component analysis
TL;DR: In this paper, the authors compared the performance of a variety of approaches for assessing the significance of eigenvector coefficients in terms of type I error rates and power, and two novel approaches based on the broken-stick model were also evaluated.
Journal ArticleDOI
Have there been recent changes in climate? Ask the fish
TL;DR: In this paper, a composite index based on three aspects of climate ocean conditions: the Aleutian Low Pressure Index, the Pacific Atmospheric Circulation Index and the Pacific Interdecadal Oscillation Index was used to measure changes in British Columbia salmon and other fish populations.
Journal ArticleDOI
Forecasting responses of seagrass distributions to changing water quality using monitoring data
TL;DR: In this paper, water quality data from 28 monitoring stations spread across the Bay were used to construct a discriminant function model that assigned a prob- ability of a given benthic habitat class occurring for a given combination of water quality variables.
Journal ArticleDOI
Statistical Series: Opportunities and challenges of sperm motility subpopulation analysis.
TL;DR: This review considers the use of statistical techniques for clustering CASA data, their challenges and possibilities, and there are many clustering approaches potentially useful for grouping sperm motility data; some options may be more appropriate than others.
Journal ArticleDOI
Effect of B-vitamins (B1, B12) and inorganic nutrients on algal bloom dynamics in a coastal ecosystem
Christopher J. Gobler,Colleen Norman,Caterina Panzeca,Gordon T. Taylor,Sergio A. Sañudo-Wilhelmy +4 more
TL;DR: The autumnal shift in phy toplankton communities from dinoflagellates to diatoms, as vitamin levels became depleted and algal communities were limited by vitamin B 12 , suggests that B-vitamins may influence the succession of coastal phytoplankon.
References
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Journal ArticleDOI
Stopping rules in principal components analysis: a comparison of heuristical and statistical approaches'
TL;DR: In this article, the authors compared several approaches to determining the number of components to interpret from principal components analysis (PCA) using simulated data matrices of uniform correlation structure and data sets of lake morphometry, water chemistry, and benthic invertebrate abundance.
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Discarding Variables in a Principal Component Analysis. I: Artificial Data
TL;DR: It is shown that several of the rejection methods, of differing types, each discard precisely those variables known to be redundant, for all but a few sets of data.
Journal ArticleDOI
Selection of Variables to Preserve Multivariate Data Structure, Using Principal Components
TL;DR: In this article, a nouvelle methode basee sur l'analyse Procrustes is proposed, and on montre qu'elle fournit un meilleur sous-ensemble for les donnees analysees en premier.
Journal ArticleDOI
Étude de la décroissance des valeurs propres dans une analyse en composantes principales: Comparaison avec le modd́le du bâton brisé
TL;DR: La variance residuelle semble se partager entre les axes restant suivant un modele proche du bâton brise, cependant l'ajustement n'est pas parfait, car la variance non due aux facteurs se repartit sur l'ensemble des axes.
Journal ArticleDOI
Assessment of sampling stability in ecological applications of discriminant analysis
Byron K. Williams,Kimberly Titus +1 more
TL;DR: Simulation results suggest that minimum sample sizes must exceed multi- variate dimensionality by at least a factor of three to achieve reasonable levels of stability in discriminant function loadings, and recommend that ecologists obtain group sample sizes that are at least three times as large as the number of variables measured.