1. Centre for Chemometrics, School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, U.K., GlaxoSmithKline, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, U.K., and GlaxoSmithKline, Old Powder Mills, Tonbridge, Kent TN11 9AN, U.K.