As agents approach animal-like complexity, evaluating them becomes as difficult as evaluating animals. This paper describes the application of techniques for characterizing animal behavior to the evaluation of complex agents. We describe the conditions that lead to the behavioral variability that requires experimental methods. We then review the state of the art in psychological experimental design and analysis, and show its application to complex agents. We also discuss a specific methodological concern of agent research: how the robots versus simulations debate interacts with statistical evaluation. Finally, we make a specific proposal for facilitating the use of scientific method. We propose the creation of a web site that functions as a repository for platforms suitable for statistical testing, for results determined on those platforms, and for the agents that have generated those results. Keywords: agent performance, complex systems, behavioral indeterminacy, repl...