William Cochran, chair of the Johns Hopkins Department of Biostatistics from 1948-1958 and widely considered to be among the most influential of American statisticians, is the father of the modern approach to the analysis of data from observational studies. He authored several landmark books, including Experimental Designs(with Gertrude Cox), Sampling Techniques,Contributions to Statistics, and Planning and Analysis of Observational Studies.
Among his many contributions, perhaps his most original were his investigations of methods for causal inference with observational data. Because of imperfect control for confounders, he developed regression and matching to control for confounding variables and investigated limitations inherent in observational research.
In addition to being a world-famous statistician, Professor Cochran was also a leading public health figure, co-authoring the 1964 Surgeon General's report that first identified tobacco as a cause of lung cancer.
Finally, Professor Cochran was a beloved teacher and mentor of young statisticians.