Data management is a critical aspect of clinical research. The plan for management of research data must be established prior to the initiation of the actual research to demonstrate rigor and transparency, with the goal of making the research reproducible. Attention must be paid to the sources of data, the method by which they will be collected and represented, and where they will be stored and maintained. Metadata should be clearly defined and existing, accepted standards should be adopted wherever possible and reasonable. Researchers must maintain a constant awareness that the data they accrue are proxies for the actual events and objects in the real world and be on guard for biases that the collection process may introduce.