Interesting reading: C. Wohlin, “Empirical Software Engineering: Teaching Methods and ConductingStudies”, in Empirical Software Engineering – Dagstuhl Seminar Proceedings (LNCS4336), pp. 135-142, edited by V. Basili, D. Rombach, K. Schneider, B. Kitchenham,D. Pfahl and R. Selby, Springer Verlag, 2007.