EMS Tables

"EMS" stands for "Expected Mean Square".

An EMS table is a method for determining the appropriate numerators and denominators for the F-tests performed during an ANOVA study. The form of the EMS table depends on several things, to include:

• the form of the model equation,

• the type of effects (fixed, random, or mixed; see link) and associated hypotheses, and

• any restrictions on randomization, to including blocking, nesting, etc.

Both Hick's and Montgomery's texts provide reasonably easy to understand instructions for creating an EMS table for a study. (see attached .pdf files for excerpts)

For an in-depth study of the theory behind fixed, random, and mixed effects models, see the book "Variance Components" by Searle, Casella, and McCulloch.