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Manual for psimpoll and pscomb

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Menu M: data analyses

Menu Me: correspondence analysis
Meg produces the submenu for data transformations: this is identical to that described for zonation (menu Mc.5). Square-root transformation effectively upweights minor taxa relative to more abundant taxa.

Within correspondence analysis itself, an additional transformation is available, the downweighting of rare types. See Meb

Standardization and centred log ration produce negative values, which cannot be used in correspondence analysis. These transformations should not be selected (the program will exit with an error message such as sqrte: Assertion `x>=0' failed).

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Copyright © 1995-2007 K.D. Bennett

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