d.4pl                   Four parameter logistic desirability function
d.central               Central values are desirable
d.ends                  Extreme (both high and low) values are
                        desirable
d.high                  High values are desirable
d.low                   Low values are desirable
d.overall               Combine individual desirabilities
d.rank                  Converts values to ranks, then ranks to
                        desirabilities
des.line                Plots a desirability function on an existing
                        graph
farmer2005              Breast cancer microarray dataset
