Some years ago, I presented a retrospective of the graph drawing (and related)experiments I had conducted since 1995 to an audience of information visualisationresearchers, describing the process I went through in defining a newexperimental research area and learning to run human–computer interactionexperiments. This was an honest and reflective seminar in which I highlightedthe mistakes I had made, the good and bad decisions, and how my knowledgeof experimental design had increased and improved with every experiment. Atthe end of my presentation, a member of the audience asked, “So, Helen, whatis the ‘Black Art’? What is it that you have learned about running experimentsthat we should all know?”

This started me thinking about how much expertise is embodied in experienceand seldom communicated apart from in a master/apprentice model.PhD supervisors can advise students on how to formulate and conduct experiments,psychology and HCI research texts can be read, and other experimentsin the research literature can be copied, but the actual step-by-step process ofdesigning and running an experiment is rarely written down and communicatedwidely. Although I believe that one can never understand the process of conductingexperiments without experiencing the process oneself, I also believethat experiences can (and should) be shared and that advice resulting fromothers’ experiences can always be useful.