Ordination or gradient analysis, in

multivariate analysis Multivariate statistics is a subdivision of statistics encompassing the simultaneous observation and analysis of more than one outcome variable. Multivariate statistics concerns understanding the different aims and background of each of the dif ...

, is a method complementary to

data clustering Cluster analysis or clustering is the task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some sense) to each other than to those in other groups (clusters). It is a main task of ...

, and used mainly in

exploratory data analysis In statistics, exploratory data analysis (EDA) is an approach of analyzing data sets to summarize their main characteristics, often using statistical graphics and other data visualization methods. A statistical model can be used or not, but pri ...

(rather than in

hypothesis testing A statistical hypothesis test is a method of statistical inference used to decide whether the data at hand sufficiently support a particular hypothesis. Hypothesis testing allows us to make probabilistic statements about population parameters. ...

). Ordination orders objects that are characterized by values on multiple variables (multivariate objects) so that similar objects are near each other and dissimilar objects are farther from each other. Such relationships between the objects, on each of several axes (one for each variable), are then characterized numerically and/or graphically. Many ordination techniques exist, including

principal components analysis Principal component analysis (PCA) is a popular technique for analyzing large datasets containing a high number of dimensions/features per observation, increasing the interpretability of data while preserving the maximum amount of information, and ...

(PCA), non-metric

multidimensional scaling Multidimensional scaling (MDS) is a means of visualizing the level of similarity of individual cases of a dataset. MDS is used to translate "information about the pairwise 'distances' among a set of n objects or individuals" into a configurati ...

(NMDS), correspondence analysis (CA) and its derivatives ( detrended CA (DCA), canonical CA (CCA)), Bray–Curtis ordination, and redundancy analysis (RDA), among others. Contemporary developments for ordination focus on machine learning techniques or using statistical models instead.

Applications

Ordination can be used on the analysis of any set of multivariate objects. It is frequently used in several environmental or ecological sciences, particularly plant

community ecology In ecology, a community is a group or association of populations of two or more different species occupying the same geographical area at the same time, also known as a biocoenosis, biotic community, biological community, ecological community, ...

. It is also used in

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

and systems biology for microarray data analysis and in

psychometrics Psychometrics is a field of study within psychology concerned with the theory and technique of measurement. Psychometrics generally refers to specialized fields within psychology and education devoted to testing, measurement, assessment, and ...

References

* , 1998. ''An Annotated Bibliography Of Canonical Correspondence Analysis And Related Constrained Ordination Methods'' 1986–1996. Botanical Institute, University of Bergen. World Wide Web: http://www.bio.umontreal.ca/Casgrain/cca_bib/index.html * 1988 ''A theory of gradient analysis.'' Adv. Ecol. Res. 18:271-313. * , Jr. 1982. ''Multivariate Analysis in Community Ecology.'' Cambridge University Press, Cambridge. * , 1995. ''Data Analysis in Community and Landscape Ecology.'' Cambridge University Press, Cambridge. * {{aut, Pagani et al., 2015. ''Methodi Ordinatio: a proposed methodology to select and rank relevant scientific papers encompassing the impact factor, number of citation, and year of publication.'' Scientometrics, December 2015, Volume 105, Issue 3, pp 2109–2135.

External links

#General #*http://ordination.okstate.edu/ The Ordination Web Page - Ordination Methods for Ecologists #*https://www.davidzeleny.net/anadat-r/doku.php/en:start #*https://link.springer.com/article/10.1007/s11192-015-1744-x #Specific Techniques #*http://www.statsoft.com/textbook/stcoran.html #*http://www.statsoft.com/textbook/stmulsca.html #*http://www.statsoft.com/textbook/glosfra.html #*https://link.springer.com/article/10.1007/s11192-015-1744-x Ordination method for articles, using year of publication, impact factor and number of citations. #Software #*http://home.centurytel.net/~mjm/pcordwin.htm #*http://www.microcomputerpower.com/catalog/canoco.html #*http://www.brodgar.com #*http://www.VisuMap.com #*https://cran.r-project.org/web/packages/vegan/vegan.pdf R package for classical ordination methods (CA,DCA,RDA,CCA) #*https://cran.r-project.org/package=seriation R package for ordering objects #*https://cran.r-project.org/web/packages/gllvm/index.html R package for model-based ordination #*https://cran.r-project.org/web/packages/VGAM/index.html R package for model-based ordination #*https://cran.r-project.org/web/packages/boral/index.html R package for model-based ordination Dimension reduction

Applications

See also

References

Further reading

External links