Among the many contributions that Kenneth ‘Ken’ O'Driscoll made to advance the understanding of radical polymerization kinetics was the implementation of proper statistical procedures for extracting (monomer) reactivity ratios from experimental data for copolymer composition. He emphasized the importance of experimental design, using non-linear regression, and a proper error analysis to construct reliable joint confidence intervals. He disseminated his views on this topic in many conferences, including the influential Santa Margherita Ligure series which he initiated, and which helped kickstart the renaissance of radical polymerization kinetics. This brief retrospective honours both Ken's scientific contributions and his humanity.