study design Box–Behnkens design Alejandra Gonzalez-Beltran Orlaith Burke Philippe Rocca-Serra The Box-Behnken design is an independent quadratic design in that it does not contain an embedded factorial or fractional factorial design. In this design the treatment combinations are at the midpoints of edges of the process space and at the center. These designs are rotatable (or near rotatable) and require 3 levels of each factor. The designs have limited capability for orthogonal blocking compared to the central composite designs. bbd(k, n0 = 4, block = (k == 4 | k == 5), randomize = TRUE, coding) from: http://artax.karlin.mff.cuni.cz/r-help/library/rsm/html/bbd.html http://www.itl.nist.gov/div898/handbook/pri/section3/pri3362.htm ready for release