PRINCIPAL COMPONENTS ANALYSIS OF DATA FROM SAXICOLOUS BRYOPHYTE VEGETATION AT STEPS BRIDGE, DEVON: II. AN EXPERIMENT WITH HETEROGENEITY

摘要

It has been suggested that the presence of heterogeneity in data may obstruct the extraction of components in principal components analysis and this is tested as follows.Heterogeneity in species-contact data collected from saxicolous bryophyte vegetation at Steps Bridge is described. The division of each of two forms of the data into two clusters is demonstrated and the results of principal components analyses of the four clusters are presented. The informativeness of a principal components analysis of the whole data is compared with that of the analyses of its constituent clusters and is shown to be the same. It is concluded that heterogeneity of the level encountered here does not reduce the effectiveness of principal components analysis.