In contrast, many modern operations research models have proven unable to reproduce historical results when they are validated; the "Atlas" model, for instance, in 1971 was shown to be incapable of achieving more than a 68% correspondence with historical results. Trevor Dupuy, a prominent American historian and military analyst known for airing often controversial views, has said that "many OR analysts and planners are convinced that neither history nor data from past wars has any relevance". In "Numbers, Predictions, and War", he implies a model that cannot even reproduce a known outcome is little more than a whimsy, with no basis in reality.