Characterization of novel substituent entropy constant by cluster analysis.
Tatsuya Takagi, Akihiro Iwata, Yoshio Sasaki, HIDEKO KAWAKI · Chemical and Pharmaceutical Bulletin · 1982
Eighteen kinds of current QSAR parameters were analysed by the cluster analysis, and divided into 4 groups, namely, cluster 1=σi, |σi|, σm, F ; cluster 2=σπ, σp, R ; cluster 3=MR, Pr, Vw, σs°, △S°, π, Es, Mw ; cluster 4=|σπ|, ι, μ. Of the eight kinds of parameters belonging to cluster 3, MR, Pr, and Vw can be substituted by σs°, whereas π (aromatic group) and Es are expressed by the linear combination of σi, σπ and σs°.