The paper presents key activities necessary for designing and analyzing an experiment in software engineering. After explaining how to choose an appropriate research technique to fit project goals, the paper shows how to state a hypothesis and determine how much control is needed over the variables involved. If control is not possible, then a formal experiment is not possible; a case study may be a better approach. Next, the six stages of an experiment (conception, design, preparation, execution, analysis and dissemination) are described, with design examined in detail. Design considerations such as replication, randomization and local control are discussed, and design techniques such as crossing and nesting are explained. Finally, data analysis is shown to be a function both of the experimental design and the distribution of the data. Throughout, examples are given to show how the techniques are interpreted and used in software engineering.