This class is good but you need to settle into it. If you really understand the homework questions and quiz questions, you will probably get an exam score that rounds to an A or a B (raw scores will be very bad) . Be okay not answering all the test questions -- just try them all and optimize for the ones you know and you will be fine. There is a lot of work but it wasnt nearly as bad as some of these other reviews make it out to be. Professor Christou cares about his students .

Professor Christou is legendary. He is the professor who truly cares about students' mental health. He holds almost every day for his office hour (even on weekends). Yes, his exams are goddam hard, but his curve is really generous, which means almost everyone fails. I have not seen any student who received below a B-. 100% recommend taking the course with him. He knows his stuff, and you can learn a lot if you try.

One of the best professor's at UCLA, only complaint would be the pace of the class and how it seems to be two quarters worth of material stuffed into one.

Yeah yeah you've read it all. Christou is TOUGH. But it's worth it. He holds office hours every day (even on Saturdays) and the TA often goes over homework problems. He assigns about 2 homework assignments every week so you will always have work to do. GO TO OFFICE HOURS. There will be like 8-15 other students there too and you can all help each other out if Christou is busy. Don't ask Christou a question if you haven't attempted it yourself. He will not give you the solution. Try something and then ask him if it's the correct approach and he will explain. To study for his exams work on organizing your notes and understanding his solutions. He will give practice exams and they are actual past exams. They are the hardest tests I have ever taken (30% is about an A, 20% is a B, etc). Look at his solutions to the exams and understand those. If you tried to attempt them on your own you will just get frustrated and stressed. All his exams are open note so organize your notes and bring EVERYTHING (you won't use everything but sometimes you refer to a process in another a homework problem). When you take his exams just try and write something down for each question. Don't worry about finishing them or having an answer (because you probably won't). If you work hard you will do well. Christou won't fail people. Overall I recommend this class even though it requires a lot of work and time. You will learn more with Christou than with any other professor.

This class can feel very overwhelming at times because the Midterms are extremely hard (average was 20/100 for both) but make sure not to get discouraged cause you will almost definitely end up with a decent grade.

I took this class over the summer and I felt okay. It's definitely hard and compacted. We went through topics very fast and the test was extremely hard. BUUUT, the curve is super nice, if you got above 30/100 then you are in the A range. Also, there are office hours almost everyday and clear handouts to help you review anything that you didn't fully get in the lectures. For those who like to take the challenge, this is a great class and you will learn a lot!

This was definitely one of the most challenging courses I have taken, but I came out of it feeling that I learned a lot. Professor Christou is tough, but he is one of the most big-hearted and passionate individuals I have ever met. You will struggle in this class, but he (and the TA) will be there for you, and his curve is super generous. You really learn to learn, not learn only to earn a good grade.

I felt like this was one of the hardest classes I've taken at UCLA up to this point, and I've really enjoyed it. Tests are brutal, but the way he curves means that it's pretty much equivalent to any other stats teacher.

Im a Math major and his exams can be compared to my hardest class M131B. The materials themselves are not as hard but his exams are enervating. His exams are harder and harder every year (I think because more Math majors are taking it now, like half of the class). I could do more than 75% of his past tests up to Fall 2017. However, the first midterm we just took was horribly hard. Most people skipped a whole section (4 questions) and many more parts lol. There are questions about beta and Cauchy distributions which we never covered in lecture. I never learned Cauchy in 100A; my friend took 100B and M170B but he never heard of it too. There are 16 "small" questions in total to be done in 2hrs. I panicked and couldn't do some really easy problems, i only realized how easy they were after turning it in. Anyways, the class is not hard, the tests are. If you dont want depression, please take someone else. Some people say you can learn more in Christou's class, yes, but you don't have to take his class, just go to his lectures before your actual class . You don't have to be suffering.
I went to attend his lectures during the summer before my actual class (also with him), so DO NOT TAKE IT IN THE SUMMER, the amount of materials is exactly the same as in a regular quarter (HW, concepts,...), so things go super fast, it moves to the next topic before you can grasp the previous ones, unless you are only taking this class.

To give you an idea about his exams, the 75th for the first midterm was 37/100, and about 40/100 for the second one. The A- and above range was 40 for the first one, and 43 for the second one.
Each exam contains about 4 parts, each parts about 4-5 "small" questions, not all questions in a part are related, so don't skip the whole part only because you don't know how to do the first question of it. He does not grade as how we think. For each "small" question you do wrong -6, if you missed just a tiny thing -1, if you are half of the way in the right direction -3, if you have something is the right direction -5. They do not add up to 100 as you can see, but at the end your score is /100. The final is also not a pleasant experience, it's difficulty level is about the same as midterms in my opinion. Even though I got A for the course, the process was really stressful.

DO NOT TAKE THIS CLASS OVER THE SUMMER!!
Despite the fact that I got an A, I would not recommend anyone taking 100B with Christou during summer because of the insane number of concepts covered in this class. It is just impossible to squeeze all of them in a six-week course.
The day before the final, we were still learning important new materials and getting new homework. This is just frustrating. I think I definitely can understand the concepts better if I take this class during regular quarters.
Regarding the tests, they are super difficult and are not similar to homework or practice. During the final, I literally "questioned my existence" and wanted to give up. For the midterm, I got 74/100 (high 94/100, median 28/100, mean 37/100). Christou said 48+ is an A, 24+(not sure) is a B.
Christou himself is a really nice professor who holds office hours EVERY DAY. He also answers emails very quickly if you have any questions. During lectures, he teaches in a fast pace, doing complicated calculations so quickly without looking at any lecture notes. He is surely a sharp and smart guy.