## principal components analysis

Mathematical technique for condensing a metabolomic spectrum to a single point on a graph, permitting rapid comparison between different species, experimental and control groups, etc.

## Principal Component Analysis Quick reference

### A Dictionary of Epidemiology (6 ed.)

...Principal Component Analysis A statistical method to simplify the description of a set of interrelated variables. Its general objectives are data reduction and interpretation; there is no separation into dependent and independent variables; the original set of correlated variables is transformed into a smaller set of uncorrelated variables called the principal components. Often used as the first step in a factor analysis. ...

## principal component analysis Quick reference

### A Dictionary of Geology and Earth Sciences (5 ed.)

... component analysis A multivariate analysis which maximizes the spread of data by plotting covariance values on sets of axes in multidimensional space allowing correlations which may have been hidden in the data to be identified. The first principal component corresponds to the first axis in multidimensional space and describes the majority of the spread of the data, subsequent higher order principal component axes are orthogonal to the first axis. Higher order axes display progressively less variation, where the data is less correlated and more...

## principal component analysis Quick reference

### A Dictionary of Media and Communication (3 ed.)

... component analysis ( PCA ) In data analytics , a statistical technique underlying most of the algorithms used to classify behavioural data ( see also Big Five ; online behavioural advertising ). This method involves rotating and reducing multiple dimensions in order to identify the strongest correlations between different categories in a data set in terms of similarities and differences . The results are used in regression models . ...

## principal component analysis Quick reference

### A Dictionary of Food and Nutrition (4 ed.)

... component analysis Mathematical technique for condensing a metabolomic spectrum to a single point on a graph, permitting rapid comparison between different species, experimental and control groups,...

##
principal-components analysis
*n.*
Quick reference

### A Dictionary of Psychology (4 ed.)

...-components analysis n . A statistical technique applied to a correlation matrix to combine observed variables into weighted linear combinations of the original variables called principal components , which are all uncorrelated with one another. The first principal component explains the maximum proportion of the variance, and successive principal components explain progressively smaller portions of the variance. This technique is closely related to factor analysis. See also cluster analysis , correspondence analysis . PCA abbrev...

## principal components analysis Quick reference

### A Dictionary of Human Geography

... components analysis ( PCA ) A method for identifying patterns (principal components) of similarity and difference in a complex dataset. PCA uses orthogonal linear transformations to convert a set of possibly correlated variables into a set of uncorrelated components. The first principal component accounts for the most variance in the data set, with subsequent components accounting for the next largest amounts. Once the principal components are determined, PCA can be used to reduce the number of dimensions within a dataset without much loss of...

## principal components analysis Quick reference

### A Dictionary of Economics (5 ed.)

...principal components analysis A technique based on the linear transformation of a multivariable data set into a smaller set of uncorrelated variables, called principal components. The first principal component accounts for as much of the variability in the data as possible, and each succeeding component accounts for as much of the remaining variability as possible. The method does not identify what these components are; this has to be inferred from outside knowledge about the processes behind the...

## principal components analysis Quick reference

### A Dictionary of Plant Sciences (4 ed.)

... components analysis A statistical technique for determining the amount of variance in a set of data, in which the first of a series of axes explains the maximum variance, the second the maximum of the variance remaining, and so forth, each axis being at right angles to the preceding one. Compare reciprocal averaging . http://www.cs.otago.ac.nz/cosc453/student_tutorials/principal_components.pdf Tutorial on principal components ...

## principal components analysis Quick reference

### A Dictionary of Geography (5 ed.)

... components analysis ( PCA ) Probably the oldest and best known of the techniques of multivariate analysis, this procedure reduces the dimensionality of a data set in which there are a large number of interrelated variables, while retaining as much as possible of the variation present in the data set. This is achieved by transforming to a new set of variables, the principal components, which are uncorrelated, and which are ordered so that the first few retain most of the variation present in all of the original variables. Demšar et al. (2013) AAAG ...

## principal components analysis Quick reference

### A Dictionary of Statistics (3 ed.)

...the diagram overleaf , the two original variables x 1 and x 2 can be replaced by the first principal component , y 1 . Principal components analysis. Principal components analysis aims to explain an n -dimensional situation using m (< n ) uncorrelated variables. Here n =2 and m =1. Let R denote the correlation matrix for the case of p x -variables. The coefficients of the x -variables corresponding to the k th principal component are the elements of the eigenvector corresponding to the k th largest eigenvalue, λ k , of R . All the...

## principal components analysis Quick reference

### A Dictionary of Social Research Methods

...principal components analysis ( PCA ) A method of exploratory factor analysis . PCA assumes that all variance is common and divides that variance among a set of components equal in number to the number of original variables. Normally only a small number of the components are then extracted in the form of latent factors. The chosen factors capture the majority of the variance on the original variables; how many factors is a matter of interpretation. By default the extracted factors are orthogonal to each other (uncorrelated). Rotation procedures can lead...

## principal components analysis Quick reference

### A Dictionary of Ecology (5 ed.)

... components analysis A statistical technique for determining the amount of variance in a set of data, in which the first of a series of axes explains the maximum variance, the second the maximum of the variance remaining, and so forth, each axis being at right angles to the preceding one. Compare reciprocal averaging . http://ordination.okstate.edu/PCA.htm Detailed explanation of the technique....

## principal components analysis

## 14 Printed Ephemera Reference library

### The Oxford Companion to the Book

...the profound, the commercial and the exhortatory—jumbled together in the context of the confused variety of everyday life. Supply-side analysis emphasizes this diversity and invariably highlights the technology of production and its relation to what could be done in the *printing office . Ephemeral print cannot be defined through the character of the organization or business through which it was produced, however. Any analysis of collecting ephemera, on the other hand, begins with the idea of consumption and indicates the ways in which the conditions for the...

## 6 The European Printing Revolution Reference library

### The Oxford Companion to the Book

...before distribution ( Jenson in Venice, *Koberger in Nuremberg). Substantial illumination was mostly added after distribution (with the exception of *presentation copies ), at the owner’s request. From the 1480s , there appears a substantial increase in the printed component of the page and a falling-off in the need for hand-finishing: woodcut initials and borders, printed running heads, and page or folio numbers are the inevitable consequence of more sophisticated *textual articulation , increased *press runs , and economic policies. The use of...

## 41 The History of the Book in Korea Reference library

### The Oxford Companion to the Book

...of the country, popular and philosophical works were produced to promote the Confucian virtues of loyalty, obedience, chastity, brotherly love, and filial piety. Clan associations issued detailed *genealogies to allow each generation to trace its family lineage, an important component of Confucian ancestor worship. Candidates for the civil service examinations studied the philosophical and literary texts that formed the syllabus of these gruelling, extended tests. Despite the restrictive nature of the economy and government control of print, then, tens of...