Randomized Complete Block Designs (RCBD)

Experimental Design in R

Joanne Xiong

Data Scientist

RCBDs

Randomized - the treatment is assigned randomly inside each block
Complete - each treatment is used the same number of times in every block
Block - experimental groups are blocked to be similar (e.g. by sex)
Design - this is your experiment!

RCBD workflow

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agricolae

library(agricolae)
trt <- letters[1:4]
rep <- 4
design.rcbd <- design.rcbd(trt,
                           r = rep,
                           seed = 42,
                           serie = 0)
design.rcbd$sketch

     [,1] [,2] [,3] [,4]
[1,] "d"  "c"  "a"  "b" 
[2,] "b"  "a"  "d"  "c" 
[3,] "d"  "a"  "b"  "c" 
[4,] "a"  "b"  "d"  "c"

Model validation - Interaction plots

with(dataset, interaction.plot(x.factor, trace.factor, response))
# example with the ToothGrowth dataset
with(ToothGrowth, interaction.plot(dose, supp, len))

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Let's practice!

Experimental Design in R