Statisticians provide crucial guidance in determining what information is reliable and which predictions can be trusted. They often help search for clues to the solution of a scientific mystery, and sometimes keep investigators from being misled by false impressions. Statisticians help determine the sampling and data collection methods, monitor the execution of the study and the processing of data, and advise on the strengths and limitations of the results. They must understand the nature of uncertainties and be able to draw conclusions in the context of particular statistical applications. Statistical planning, analysis, and inference is so crucial to the kind of research conducted by Hopkins GIM researchers that the Division has built a cadre of in-house methodologists, trained in epidemiology and biostatistics, who work side-by-side with content-oriented clinical researchers and their trainees.