Even at the World Bank and USAID, only a small portion of projects are subject to impact evaluations, agreed Amanda Glassman, chief operating officer and senior fellow at the Center for Global Development. Every year, her group does an exhaustive review to identify large-scale health programs that made a big impact. Of about 250 that they looked through this past year, "only 50 used rigorous methods to establish the attributable impact. And none of the very largest programs in global health had done any impact evaluation" of the type she argues are needed — including two major international nonprofit organizations: Global Fund to Fight AIDS, Tuberculosis as well as GAVI, the Vaccine Alliance. This doesn't mean the health products that these health programs use — medicines or vaccines, for instance — haven't been proven effective through, say, medical trials or studies of what happens to the incidence of disease when you vaccinate a certain population, explained Glassman.