Yields from treatment for mildew control
A data frame with 38 observations on the following 4 variables.
treatment factor, 4 levels
block factor, 9 levels
grain yield, tons/ha
There were four spray treatments: 0 (none), 1 (early), 2 (late), R (repeated).
Each treatment occurs once between each of the 9 ordered pairs of the other treatments.
The first and last plot are not assigned to a block.
Norman Draper and Irwin Guttman (1980). Incorporating Overlap Effects from Neighboring Units into Response Surface Models. Appl Statist, 29, 128–134. http://doi.org/10.2307/2986297
Maria Durban, Christine Hackett, Iain Currie. Blocks, Trend and Interference in Field Trials.
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data(jenkyn.mildew) dat <- jenkyn.mildew require(lattice) bwplot(yield ~ trt, dat, main="jenkyn.mildew", xlab="Treatment") # Residuals from treatment model show obvious spatial trends m0 <- lm(yield ~ trt, dat) xyplot(resid(m0)~plot, dat, ylab="Residual", main="jenkyn.mildew - treatment model") # The blocks explain most of the variation m1 <- lm(yield ~ trt + block, dat) xyplot(resid(m1)~plot, dat, ylab="Residual", main="jenkyn.mildew - block model")
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