1. A computer program product for creating mappings between taxonomies, the computer program product comprising: a computer readable storage device having computer readable program code embodied therewith, the computer readable program code configured to: classify documents from a category of a taxonomy to one or more categories within a master taxonomy based on a statistical model and classification score values, wherein the classification score values indicate whether the documents belong in a corresponding category of the master taxonomy; analyze the document classifications to determine a mapping between the taxonomy category and the corresponding category of the master taxonomy, a rule-based mapping is automatically created that maps the taxonomy category to the corresponding category in the master taxonomy in response to classification score values for the documents being above a threshold and in response to a majority of documents of the taxonomy category being classified within a single corresponding category of the master taxonomy; analyze the document classifications to identify outlier documents within the taxonomy category to determine whether the outlier documents should belong to the corresponding category; and update the statistical model when the outlier documents should belong to the corresponding category.