CEPSHUFL & SOLCOMP: Permuting CEP data files and analysing ordination stability
Tausch et al. (Journal of Vegetation Science, 6, 897-902; 1995) found out that some programs for Correspondence Analysis were dependent on the input order of species and sites. Peter Michin and me have studied the performance of CANOCO (Journal of Vegetation Science, 8, 477-454; 1997: abstract), and found that it is unstable to some degree as well. Further, we have been able to identify and remove the reasons of this instability. Some of the following programs (CASVD, debugged & strict DECORANA, strict TWINSPAN) are aimed to be used for correcting the observed instability.
CEPSHUFL and SOLCOMP are a pair of programs to analyse the stability of CANOCO ordinations under change of data input order. CEPSHUFL reads CEP or CANOCO formatted data files and permutes randomly both species and sites. SOLCOMP reads CANOCO solution files from the original data file and from permuted data file, and analyses the statiblity of the ordination results. These programs are intended to be used together (see manual).
CEPSHUFL and SOLCOMP come now (from 17/9/97) together with a utility program STABLTY which performs with a single command a CANOCO stability analysis for PCA, RDA, CA, CCA, DCA or DCCA. For more details, see its readme file.