Okay, first, (PS: when i really curious about the study of IE and how to keeping good control on any production system) i realize it's a goddess of statistical control book (if not mistaken, in Francaise, book is a female. am i right?). nice distribution introducing in foreword but a little bit confusing when i knew that my teacher did'nt use it as a reference book, and i got C for that. . How comee???