The difference between the traditional robust design approach and the new one are discussed in this article. The traditional engineering way for functionality is as follows. Design a product or a process to perform its intended function at normal condition at first, then improve its functionality at various noise conditions by minimizing the mean square deviation from the intended function. The new way improves the functionality first, considering all variables happened at customer's conditions are either signal or noise where the signal should have an intended function but noises should not, then adjust the function to meet the intended function at only norrnal initial condition by least square methods.