This data is taken from Snedecor and Cochran (1980) and corresponds to a true matched pairs experiment. The data originally came from Youden and Beale in 1934 who "wished to find out if two preparations of a virus would produce different effects on tobacco plants. Half a leaf of a tobacco plant was rubbed with cheesecloth soaked in one preparation of the virus extract, and the second half was rubbed similarly with the second extract." (Page 86, Snedecor and Cochran, 1980) Each of the 8 points in the figure corresponds to the numbers of lesions on the two halves of one leaf with sides that had been treated differently.
A dataframe with 8 observations on the following 2 variables, no NAs
Virus Preparation 1
Virus Preparation 2
Youden, W. J., Beale, H. P. (1934). A statistical study of the local lesion method for estimating tobacco mosaic virus. In Contributions from Boyce Thompson Institute 6, page 437.
Snedecor, W., Cochran, W. (1980). Statistical methods. Iowa State University Press, Ames Iowa, seventh edition.