1. A computer-implemented method of process analysis comprising the steps of: (a) performing a first manufacturing operation including a predetermined process to obtain a first number of products; (b) performing a second manufacturing operation differing from said first manufacturing operation only in details associated with said predetermined process to obtain a second number of products of the same kind as those obtained by said step (a); (c) determining whether or not a predetermined effect is achieved with respect to each of said products obtained by said steps (a) and (b); (d) classifying said products obtained by said steps (a) and (b) into four categories depending on which of said first manufacturing operation and said second manufacturing operation has been performed, and on whether or not said predetermined effect has been achieved; and (e) analyzing a degree of achievement of said predetermined effect exhibited by said predetermined process based on classification of said step (d), to provide an analysis result.