DATA:      Van der Aart & Smeek-Enserink (1975)
DIRECTORY: \CANOCO\SAMPLES\UNIMODAL\SPIDER2
PROBLEM:   Determination of the niches of hunting spiders in a dune area by CCA
BOOKLET:   pp 63-67
ILLUSTRATION OF:
+ CCA interpretation.
+ How to interpret numbers in the file SPEC_ENV.TAB.
+ How to define products of explanatory variables using the Define Interaction
  Terms option.
+ How to choose names for environmental variables when products are to be 
  defined.
+ Potential problems when there are many environmental variables and how to 
  cope with them.
_______________________________________________________________________________
FILE TYPE    |  FILE NAME    |         DESCRIPTION
-------------+---------------+-------------------------------------------------
 SPECIES     | spid_spe.dta  | counts of 12 hunting spiders in 28 pitfalls in 
             |               | a dune area
ENVIRONMENT  | spid_env.dta  | 6 soil and vegetation variables for 28 pitfalls
             |               | (ln-transformed)
             | spiden26.dta  | 26 soil and vegetation variables for 28 pitfalls
             |               | (ln-transformed)
 DERIVED     | wa_6.dta      | Weighted averages of spiders with respect to 
             |               | the 6 environmental variables (copy of 
             |               | spec_env.tab from spider.con)
             | wa_all.dta    | Weighted averages of spiders with respect to all
             |               | 26 environmental variables (copy of spec_env.tab
             |               | from ca_all.con)
 PROJECTS    | spider.con    | CCA of square-root transformed spider counts 
             |               | on 6 environment variables (ln-transformed)
             | cca_all.con   | CCA of square-root transformed spider counts on 
             |               | all 26 environment variables (ln-transformed)
             | ca_all.con    | CA of square-root transformed spider counts,
             |               | interpreted using all 26 environment variables
             |               |  (ln-transformed)
             | cca_all2.con  | CCA of square-root transformed spider counts on 
             |               | 28 samples and 27 environment variables
             | forward.con   | CCA with forward selection using all 26 
             |               | environment variables
-------------+---------------+-------------------------------------------------
  
Van der Aart, P.J.M. & Smeenk-Enserink, N.(1975): Correlations between
distribution of hunting spiders (Lycosidae, Ctenidae) and environmental
characteristics in a dune area. Neth. J. Zool., 25: 1-45.