Returns a model formula that can be used to fit (in general) an effect
saturated model using the function fac.aov. This function is
used to generate the default formula in a typical call to fac.aov.
USAGE:
formula.fac.design(object, response)
REQUIRED ARGUMENTS:
object:
an object of class "fac.design", typically created using
design.digest, fac.design, or as.fac.design.
OPTIONAL ARGUMENTS:
response:
the response variable. The default is to use the first
non-factor in the fac.design object.
VALUE:
an object of class formula that typically will specify an effect
saturated model for the fac.design object.
DETAILS:
The effect saturated model is generated as a fully crossed model if
there are fewer than seven factors (e.g., y~A * B * C * D) and a
crossed model of order 3 for seven or more factors (e.g., y~.^3 ). The
presence of a factor named "Quad" indicates that there are
center points and a term "Quad" that does not interact with any model
terms will be added to the model. If there is a blocking factor, it
will be added as the first term in the formula
(e.g., y ~ Block1 + A*B*C*D + Quad).
a.design <- design.digest('ff0816')
formula(a.design)
formula(buffer.df)
# the following two statements are equivalent
fac.aov(formula(buffer.df),data=buffer.df)
fac.aov(buffer.df)