weiss.lattice | R Documentation |
Lattice experiment in soybeans.
data("weiss.lattice")
A data frame with 196 observations on the following 5 variables.
yield
yield (bu/ac)
gen
genotype factor, 49 levels
rep
rep factor, 4 levels
col
column
row
row
Yield test of 49 soybean varieties, grown at Ames, IA, in 1938. Plot dimensions were 3x16 feeet. The varieties are compared to variety 26 (Mukden).
It is not clear how the reps were positioned in the field. On the one hand, the middle three columns of each rep/square are higher yielding, giving the appearance of the reps being stacked on top of each other. On the other hand, the analysis by Weiss uses 24 degrees of freedom 4*(7-1) to fit a separate effect for each column in each rep (instead of across reps).
Weiss, Martin G. and Cox, Gertrude M. (1939). Balanced Incomplete Block and Lattice Square Designs for Testing Yield Differences Among Large Numbers of Soybean Varieties. Table 5. Agricultural Research Bulletins, Nos. 251-259. https://lib.dr.iastate.edu/ag_researchbulletins/24/
## Not run:
library(agridat)
data(weiss.lattice)
dat <- weiss.lattice
libs(desplot)
desplot(dat, yield~col*row|rep,
text=gen, shorten="none", cex=.8, aspect=3/16, # true aspect
main="weiss.lattice (layout uncertain)", xlab="Soybean yields")
dat <- transform(dat, xf=factor(col), yf=factor(row))
m1 <- lm(terms(yield ~ rep + rep:xf + rep:yf + gen, keep.order=TRUE), data=dat)
anova(m1) # Matches Weiss table 7
## Response: yield
## Df Sum Sq Mean Sq F value Pr(>F)
## rep 3 91.57 30.525 4.7414 0.0039709 **
## rep:xf 24 2913.43 121.393 18.8557 < 2.2e-16 ***
## rep:yf 24 390.21 16.259 2.5254 0.0007734 ***
## gen 48 1029.87 21.456 3.3327 2.652e-07 ***
## Residuals 96 618.05 6.438
# ----------
if(require("asreml", quietly=TRUE)){
libs(asreml)
m2 <- asreml(yield ~ rep + rep:xf + rep:yf + gen, data=dat)
# Weiss table 6 means
wald(m2)
predict(m2, data=dat, classify="gen")$pvals
## gen pred.value std.error est.stat
## G01 27.74 1.461 Estimable
## G02 24.95 1.461 Estimable
## G03 24.38 1.461 Estimable
## G04 28.05 1.461 Estimable
## G05 19.6 1.461 Estimable
## G06 23.79 1.461 Estimable
}
## End(Not run)
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