Yield data from a Minnesota barley trial

Description

Total yield in bushels per acre for 10 varieties at 6 sites in each of two years.

Usage

barley

Format

A data frame with 120 observations on the following 4 variables.

yield

Yield (averaged across three blocks) in bushels/acre.

variety

Factor with levels "Svansota", "No. 462", "Manchuria", "No. 475", "Velvet", "Peatland", "Glabron", "No. 457", "Wisconsin No. 38", "Trebi".

year

Factor with levels 1932, 1931

site

Factor with 6 levels: "Grand Rapids", "Duluth", "University Farm", "Morris", "Crookston", "Waseca"

Details

These data are yields in bushels per acre, of 10 varieties of barley grown in 1/40 acre plots at University Farm, St. Paul, and at the five branch experiment stations located at Waseca, Morris, Crookston, Grand Rapids, and Duluth (all in Minnesota). The varieties were grown in three randomized blocks at each of the six stations during 1931 and 1932, different land being used each year of the test.

Immer et al. (1934) present the data for each Year*Site*Variety*Block. The data here is the average yield across the three blocks.

Immer et al. (1934) refer (once) to the experiment as being conducted in 1930 and 1931, then later refer to it (repeatedly) as being conducted in 1931 and 1932. Later authors have continued the confusion.

Cleveland (1993) suggests that the data for the Morris site may have had the years switched.

Author(s)

Documentation contributed by Kevin Wright.

Source

Immer, R. F., H. K. Hayes, and LeRoy Powers. (1934). Statistical Determination of Barley Varietal Adaptation. Journal of the American Society of Agronomy, 26, 403–419.

Wright, Kevin (2013). Revisiting Immer's Barley Data. The American Statistician, 67(3), 129–133.

References

Cleveland, William S. (1993) Visualizing Data. Hobart Press, Summit, New Jersey.

Fisher, R. A. (1971) The Design of Experiments. Hafner, New York, 9th edition.

See Also

immer in the MASS package for data from the same experiment (expressed as total yield for 3 blocks) for a subset of varieties.

Examples

# Graphic suggesting the Morris data switched the years 1931 and 1932
# Figure 1.1 from Cleveland
dotplot(variety ~ yield | site, data = barley, groups = year,
        key = simpleKey(levels(barley$year), space = "right"),
        xlab = "Barley Yield (bushels/acre) ",
        aspect=0.5, layout = c(1,6), ylab=NULL)