Ronald A. Fisher was "interested in application and in the popularization of statistical methods and his early book Statistical Methods for Research Workers; published in 1925; went through many editions and motivated and influenced the practical use of statistics in many fields of study. His Design of Experiments (1935) [promoted] statistical technique and application. In that book he emphasized examples and how to design experiments systematically from a statistical point of view. The mathematical justification of the methods described was not stressed and; indeed; proofs were often barely sketched or omitted altogether ...; a fact which led H. B. Mann to fill the gaps with a rigorous mathematical treatment in his well known treatise; Mann (1949)."

Mann, H. B. (1949). Analysis and design of experiments: Analysis of variance and analysis of variance designs. New York; N. Y.: Dover Publications; Inc. pp. x+195. MR 0032177.