design
object.
alias.design(object, formula= ~ ., ...)
.^2
; i.e.,
all main effects and second-order interactions.
This function is a method for the generic function
for class design.
It can be invoked by calling
for an object x of the appropriate class, or directly by calling
regardless of the class of the object.
A formula is needed if you want a non-default model, and always
if there are covariates you want to include in the model.
The formula need not have a left side; an artificial response will
be used.
The numerical result does not depend on the value of the response,
but interpretation of
.
in the formula does, so if you want
a non-factor to be excluded from a formula using
.
, it should
be in the response.