Morris H. Hansen (1910-1990): Hansen was, perhaps, the most influential statistician in the evolution of survey methodology in the 20th century. Early in his Census Bureau career, Hansen assembled and directed a team of mathematical statisticians and other survey methodologists. The team defined and researched the principal problems in the taking of surveys and developed the statistical methods needed for large-scale national surveys. These included formal quality control methods and the derivation of theory and models for analyses of non-sampling errors. He co-authored (with William N. Hurwitz and William C. Madow, also Census Bureau employees) a two-volume statistical text, Sample Survey Methods and Theory. In Revolution in United States Statistics, Joseph Duncan and William Shelton called the the second volume, "Theory", "the most important book produced by federal employees on sampling and one of the most important books on methods produced as an offshoot from the federal statistical system." Hansen participated in the Census Bureau's oral history program [PDF 656k].