DATA:      B. Post (1983: unpublished)
DIRECTORY: \CANOCO\SAMPLES\UNIMODAL\WEEDS
PROBLEM:   Detection of a spatial gradient in vegetation data
BOOKLET:   pp 79
ILLUSTRATION OF:
+ How to destandardize canonical coefficients
+ The arbitrariness of the sign of an ordination axis
+ How to interpret large "Covariable influence" without covariable data
+ Means, standard deviations and correlations in CCA versus RDA
+ How to obtain means, standard deviations and correlations of variables
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FILE TYPE    |  FILE NAME    |         DESCRIPTION
-------------+---------------+-------------------------------------------------
 SPECIES     | weeds.dta     | counts of 13 arable weeds across a barley field 
             |               |  (96 plots)
ENVIRONMENT  | xy_coord.dta  | spatial coordinates of the plot centres
 PROJECTS    | trend.con     | CCA of weeds on spatial coordinates
             | cca_sqrt.con  | CCA of weeds on spatial coordinates 
             |               |  (square-roots of counts)
             | rda_sqrt.con  | RDA of weeds on spatial coordinates 
             |               |  (square-roots of counts) 
-------------+---------------+-------------------------------------------------