Robin Henderson studied Mathematics in Professor Alexander Aitken's department at the University of Edinburgh. Professor Aitken developed the matrix formulation of linear regression models that is employed in statistical software packages such as MINITAB1. Following graduation, the author trained as a secondary school teacher and began his career in education at Boroughmuir School, Edinburgh. Since 2001, Robin has been operating as a sole consultant, trading as Halcro Consultancy, Loanhead, providing training and consultancy in statistics for quality improvement and Six Sigma. He has assis...