Chapter 14 Linear Mixed-Effects Models for Data from Split-Plot Experiments

An example Split-Plot Experiment

• this experiment has two factors: genotype and fertilizer
• genotype is caller the whole-plot factor because its levels are randomly assigned to whole plots
• fertilizer is called the split-plot factor because its levels are randomly assigned to split plots within each whole plot
• we have two different sizes of experimental units: whole plots are the whole-plot experimental units and split-plots are the split-plot experimental units

Why Use a Split-Plot Design?

• Split-plot designs usually arise because logistical constraints make a CRD or RCBD impractical.
• For example, it may be easier to change from one fertilizer level to another as a tractor drives through a field, while it may be more difficult to change from planting one genotype to planting another.
• In the engineering literature, split-plot designs are sometimes called designs with hard-to-change factors.

Another split-plot experimental design:

• Diet is the whole-plot treatment factor.
• Litters are the whole-plot experiment units.
• Drug is the split-plot treatment factor.
• Mice are the split-plot experiment units.