garber.multi.uniformity {agridat}R Documentation

Uniformity trials of oat hay and wheat grain


Uniformity trials of oat hay and wheat grain, at West Virginia Agricultural Experiment Station, 1923-1924, on the same land.


A data frame with 270 observations on the following 4 variables.






yield of oat hay


yield of wheat grain


Each plot was 68 feet x 21 feet. After discarding a 3.5 foot border on all sides, the harvested area was 61 feet x 14 feet. The plots were laid out in doubles with a 14-foot roadway between the plots.

Note: The orientation of the plots is a guess.

Field width: 6 plots * 68 feet + 14 ft/roadway * 2 = 436 feet

Field length: 45 plots * 21 feet/plot = 945 feet

In 1923 the field was planted to oats and harvested as hay.

In 1924 the field was planted to wheat and harvested for grain.

Garber: "Plots 211 to 214, and 261 to 264, [note, these are rows 11-14, columns 5-6] inclusive, were eliminated from this study because of the fact that a few years ago a straw stack had stood on or in the vicinity...which undoubtedly accounts for the relatively high yields on plots 261 to 264, inclusive."

Note: The source document contained mean-subtracted yields. The oat yield in row 22, column 5 was given as +59.7. This is obviously incorrect, since the negative yields all end in '.7' and positive yields all ended in '.3'. We used -59.7 as the centered yield value and added the mean of 1883.7 to all centered yields to obtain absolute yields.

Note: Another paper by these authors, "A Method of Laying Out Experimental Plats", contains three additional years of uniformity trials, with each crop expressed as a percentage.


Garber, RJ and Mcllvaine, TC and Hoover, MM. 1926. A study of soil heterogeneity in experiment plots. Jour Agr Res, 33, 255-268. Tables 3, 5.


## Not run: 

  dat <- garber.multi.uniformity

  desplot(dat, oats ~ col*row,
          flip=TRUE, tick=TRUE, aspect=945/436, # true aspect
          main="garber.multi.uniformity oats")

  desplot(dat, wheat ~ col*row,
          flip=TRUE, tick=TRUE, aspect=945/436, # true aspect
          main="garber.multi.uniformity wheat")

  with(dat, cor(oats, wheat)) # = .37 matches Garber

## End(Not run)  

[Package agridat version 1.18 Index]