This class was a rollercoaster tbh. Of course, people say it's one of the hardest stats classes at UCLA, and though that's true, I think how I did in this class really depended on Xu as a professor. He followed the textbook extremely closely, so I relied on the book for a lot of my studying for the class. In fact, a lot of his homework questions were actually taken from the textbook, so there's a little tip if you're every stuck on homework. His first midterm was really tricky and the average was like a 50%, but then he made the class super easy and both his second midterm and final were really straightforward and simple, so I ended with an A in the class. So, overall, I think the class was doable, but I didn't like Xu as a professor all that much. He was pretty boring and not that helpful - I've heard he's pretty standoffish during office hours. However, my TA, Linfan Zhang, helped a lot in this class! She was always super helpful during office hours and gave me so many tips on the homework.

I took Stats 100B with Professor Xu and it was definitely enjoyable. He makes the concepts clear and his exams are very fair. If you read the text books, go to office hours, and actually do the homework, the exams won't be too bad. All the bad reviews he gets are from people who just didn't want to work hand and expected to be spoon fed. The homework is very doable and reflect well on what he tests on. His exams are very straightforward, so if you know the concepts, understand the homework, practice the actual calculations, and pay attention to details, you will succeed in the class. Also, he's very funny and chill to talk to in office hours and he will help you if you go ask him questions.

Since he used to be in pure math major,he tries to make stat class more like math class, in my view. If you have no interest or not good at proving something, you had better not take him. He basically follows everything from the book, which is easy for you to study the material again after class. I really recommend you to go to office hour. He is willing to talk with you about everything, not only the material covered in the class, but also sometimes about his research. Anyway, he is a very nice person.
Discussion is useful as well, since TA will talk about the homework for sure, and mostly you can get all the answer for homework, since she has solution shhh. But TA's office hour is useless.

This was Professor Xu's first time teaching 100B and he closely followed the textbook, so the lectures were pretty dry in my opinion. There was also no random sign-in sheet that was passed around.

Homework problems were mostly taken from Professor Christou's homeworks.
The exams were straightforward, but they were not open book/notes. We did not get to use a calculator until the final.

He had two grading schemes: Straight scaling and curving. For curving he would give top 25% A, next 25% B, and so forth. For the curving grading scheme, he said he would fail people if they did really bad in the class, e.g. 40 on final.

Although I have never been to his office hours, I have heard he is extremely helpful during them.