This is a book targeting actors in the field of marketing – academic researchers, practitioners, market analysts, teachers and students – with an interest in how customers are influenced by marketing. The main argument is that the experiment constitutes a powerful method for revealing the influence of various marketing activities. Basically, an experiment means that individuals are randomly allocated to groups, which receive different treatments, followed by a comparison of the groups’ reactions after the treatments. To conduct experiments along these lines, however, involves several choices and challenges, and the ambition with this book is to offer guidelines to experimenters who wish to come to terms with influence-related issues in a marketing context.