The statistician who supposes that his main contribution to the planning of an experiment will involve statistical theory, finds repeatedly that he makes his most valuable contribution simply by persuading the investigator to explain why he wishes to do the experiment, by persuading him to justify the experimental treatments, and to explain why it is that the experiment, when completed, will assist him in his research. A quote from American statistician, and founder of the North Carolina State University Department of Statistics, Gertrude Cox (1900-1978). The quote is from a speech delivered at the Department of Agriculture in Washington D.C. on January 11th, 1950. The quote also appears in Chapter 1 of W.E. Deming's 1960 book "Sample Design in Business Research".
