formula.design(object, multiy = T)

object:

any object inheriting from class "design".

multiy:

if more than one non-factor is included in the design variables, should the response be all these combined using cbind(), or just the first one.

This is a method for the function formula() for objects inheriting from class design. The variable(s) in the design which do not inherit from "factor" are candidates for the response. Depending on multiy, all or only the first will be used. If multiy is FALSE, extra non-factors are not included in the formula; that is, quantitative covariates are not included automatically. See the example.

sapply(wafer, function(x)inherits(x,"factor"))

# produces the following output:
maskdim visc.tem spinsp baketime aperture
      T        T      T        T        T

exptime devtime etchtime pre.mean pre.dev
      T       T        T        F       F

post.mean post.dev N
        F        F F

# second example:
formula(wafer, multiy = F)

#produces the following output:
pre.mean ~ maskdim + visc.tem + spinsp +
        baketime + aperture + exptime + devtime +
        etchtime + pre.mean