These estimates were derived by Imperial College London, as part of the WHO Ebola Response Team, from data provided by the WHO. Information on the data cleaning processes and the calculation of case fatality rate (CFR) can be found in the New England Journal of Medicine papers, Ebola Virus Disease in West Africa — The First 9 Months of the Epidemic and Forward Projections and West African Ebola Epidemic after One Year — Slowing but Not Yet under Control. The data sources were the Viral Hemorrhagic Fever patient databases for Guinea, Liberia, and Sierra Leone.