Pierre Louis (1787-1872), French physician. Louis carried out most of his work at the Charite and Hotel-Dieu, large hospitals in Paris, France. He used statistics (what he termed the numerical method") to check the effectiveness of various medical techniques. In 1828, he showed that bloodletting using leeches was generally of little use in treating disease. Louis also used statistics in his works on tuberculosis (1825) and typhoid (1829). The methods he used were important in establishing new medical techniques and the statistical techniques used in modern drug trials."