A Meredith and Bridge used the yield results of cotton breeders' advanced strain tests, in which one or two check cultivars were grown in each test, to adjust yields. The pooled regression equation for the mean of all of the advanced strains over the same time measures changes in yield due to both environmental and genetic causes. It is obvious that cotton improvement has been conducted since early times, and no doubt genetic contributions to yield and quality were made, but data are not available to calculate accurate measurements of early progress. The development of scientific cotton breeding is attributed to the hiring of Dr. Herbert J. Webber as a cotton breeder by the US Department of Agriculture in 1898. Between 1900 and 1910 scientific cotton breeding was started by Coker's Pedigreed Seed Company, Clemson College, and the Mississippi Agricultural Experiment Station.