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THE USE OF RATIO VARIABLES IN SYSTEMATICS
Author(s) -
Frampton C. M.,
Ward J. M.
Publication year - 1990
Publication title -
taxon
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 81
eISSN - 1996-8175
pISSN - 0040-0262
DOI - 10.2307/1223364
Subject(s) - statistics , mathematics , a priori and a posteriori , variable (mathematics) , variables , systematics , set (abstract data type) , econometrics , biology , computer science , ecology , taxonomy (biology) , mathematical analysis , epistemology , philosophy , programming language
Summary Eight ratio variables measured on 85 OTUs from Raoulia subg. Raoulia were studied to explore their distributional properties and discriminating abilities. The ratios are shown to be generally less normal than their constituents, a property that can (to varying degrees) be alleviated by the choice of the numerator as the constituent with the largest coefficient of variation. The discriminating properties of the ratios are shown to be as good as their constituents individually, implying that the ratios are potentially useful variables with unique properties. The problem of redundant variability as a product of including a ratio variable and its two constituents in a data set is also addressed. Given that the deletion of one of these variables is a solution to this, it is shown that removing the ratio does not necessarily optimise the amount of retained variability. Thus, the use of ratio variables is seen to be an empirical a posteriori decision that can be made on the basis of objective criteria.