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

This started me thinking about how much expertise is embodied in experience and 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 experiments in the research literature can be copied, but the actual step-by-step process of designing and running an experiment is rarely written down and communicated widely. Although I believe that one can never understand the process of conducting experiments without experiencing the process oneself, I also believe that experiences can (and should) be shared and that advice resulting from others’ experiences can always be useful.