Using observational pilot studies to test and improve lab packages

Controlled experiments are a key approach to evaluate and evolve our understanding of software engineering technologies. However, defining and running a controlled experiment is a difficult and errorprone task. This paper argues that one can significantly reduce the risks associated with defining a new controlled experiment by running a set of well-planned observational pilot studies aimed at improving the experimental material. It gives the steps for such an approach and illustrates it with a case study that shows the definition of an experiment to evaluate inspection techniques for information visualization tools through a set of four observational studies and one experimental trial. Based on the lessons learned we present some guidelines on how to test and improve experimental material in such way.