I am leaving a review after reading the 5th Big Data Analysis article. (Total 4 subjects) First of all, all instructors explain the contents of the lecture well to grasp the concepts. They especially focus on concepts that appear in high-frequency problems. As a disadvantage, some lectures follow the recommended book's progress and the order is slightly changed (not all). Also, the recommended book is focused on many mock exams rather than detailed explanations, making it difficult to solve the problems. You have to get answers through questions. On the other hand, there were additional concepts that were introduced for reference considering the lecture time among the concepts that are not in the book, which was confusing. In addition, the reason why you have to listen to PART 3 and 4 instead of this lecture is that you have to listen to the explanation at least in PART 3 to understand. However, you can memorize PART 4. This is related to the difficulty of the exam. Lastly, since the Big Data Analysis Engineer exam is also a test for engineers, I recommend that you only watch the lectures to the extent of asking and answering questions and understanding the concepts (don't just skip over them) rather than listening to the lectures repeatedly, and memorize the concepts of the problems that appear in the mock exams or exams.