Experimental economics is now a well-recognized method in economics, and experimental papers are published routinely in top economics journals. Research in experimental economics often involves recruiting subjects to come to a lab to make choices in decision-making situations we have designed and which we then study. Other times it involves recruiting firms or government agencies to run an experiment in the field. It always involves actively gathering data under conditions that we create as experimenters, as opposed to gathering naturally-occurring data, such as stock prices or unemployment figures. Our control over these conditions, and the ability to create necessary counterfactuals, allow us, in some cases, to answer questions that are difficult to address with naturally-occurring data.