factorial and split-plot statistical designs

factorial and split-plot designs are two statistical procedures used to conduct agricultural field experiments. both designs are used frequently to quantify the main and interaction effects of two or more factors. however, split-plot design is recommended for specific situations depending on major and minor goals of the study, characteristics of the factors, and precision of statistical testing mentioned in this note. in field experiments, when date of planting is one of the factors, split-plot design should be used. the reasons are explained in detail in the note. using a factorial instead of a split-plot design when date of planting is a factor would result in data confounded with other external environmental variation and therefore the results obtained would not be statistically valid.