I have done the skin type questionnaire in the book but I am having a problem determining whether I am an O or a D type skin. I scored 25.5 the first time and when I went back to check the accuracy of my outcome was still a 25.5. I even tested my skin for some of the questions. I want to buy new skin care product based on the recommendations in the book but am not sure whether to follow the ORPT chapter or the DRPT chapter.