potatoes {sfsmisc} | R Documentation |
Fisher's potato crop data set is of historical interest as an early example of a multi-factor block design.
data(potatoes)
A data frame with 64 observations on the following 5 variables.
1:4
.A
to H
and
J
to Q
, i.e., LETTERS[1:17][-9]
.0,1,2,4
.0,1,2,4
.Bennett, J. H. (1972) Collected Papers of R. A. Fischer vol.~II, 1925-31; The University of Adelaide.
T.Eden and R. A. Fisher (1929) Studies in Crop Variation. VI. Experiments on the Response of the Potato to Potash and Nitrogen. J. Agricultural Science 19, 201–213. Accessible from Bennett (1972), see above.
data(potatoes) ## See the experimental design: with(potatoes, { cat("4 blocks of experiments;", "each does every (nitrogen,potash) combination (aka 'treat'ment) once.", '', sep="\n") print(ftable(table(nitrogen, potash, treat))) print(ftable(tt <- table(pos,potash,nitrogen))) tt[cbind(pos,potash,nitrogen)] <- as.character(treat) cat("The 4 blocks pos = 1, 2, 3, 4:\n") ftable(tt) }) ## First plot: with(potatoes, interaction.plot(potash,nitrogen, response=yield)) ## ANOVAs: summary(aov(yield ~ nitrogen * potash + Error(pos), data = potatoes)) # "==>" can use simply summary(aov(yield ~ nitrogen + potash + pos, data = potatoes)) # and summary(aov(yield ~ nitrogen + potash, data = potatoes))