The formula must have a left hand side that can be converted to a logical.
makeDesigns(fmla, data)
DesignOptions
Formula
Data
On the RHS: - It may have at most one cluster() argument. - It may have one or more strata() arguments. - All other variables are considered covariates.
NAs in a cluster() or strata() variable will be dropped. NAs in covariates will be passed through, but without being flagged as NotMissing (as available data items will)