Biostatistics is the branch of statistics responsible for the proper interpretation of scientific data generated in the biology, public health and other health sciences (i.e., the biomedical sciences). In these sciences, subjects (patients, mice, cells, etc.) exhibit considerable variation in their response to stimuli. This variation may be due to different treatments or it may be due to chance, measurement error, or other characteristics of the individual subjects. Biostatistics is particularly concerned with disentangling these different sources of variation. It seeks to distinguish between correlation and causation, and to make valid inferences from known samples about the populations from which they were drawn.