The various models and reference data included in STEM are provided as examples of how users can create and define their own models and data. While effort was/is made to ensure the data reflects information available today in the public domain, we do not represent or guarantee the accuracy of data or of the original sources including populations, area, population densities, geographic information (precise latitudes and longitudes, etc). In some cases estimations were used to provide approximations for population densities where no public data could be found. The mathematical models included in STEM are based on standard textbook models like, for example, the SIR or SEIR models. Users are free to adjust the rate constants in these mathematical models to create their own approximations or models of infectious disease. In addition to changing rate constants, advanced users will want to code their own mathematics extending the simple base models. We do not represented or guarantee that the simple base models included in STEM are "optimal" for any particular infectious disease and creation of a "good" model for real disease is part of modern state of the art epidemiological research. STEM is provided as a Framework to support this research in which users may create and exchange their own models. We do claim to implemented "best" or even "accurate" models for any particular disease. Over time we will build into STEM tools that will allow users to do their own validation studies of various models.