Avoid this professor. All other reviews for 170s were during online quarters due to COVID, ie 24 hour exams. I took this class fully in person with timed exams, and I would say it is the worst math class I have taken here (even compared to math 115a in person). The grade is only composed of quizzes and exams, where quizzes are 24 hour and easy, but do not reflect difficulty of exams and are very surface level. The first midterm and the final were completely unreasonable in terms of difficulty. The mean for midterm 1 was around 50. He gives optional homework which are just book problems and does not provide any solutions or explanations to check with, so if you don't have Chegg you are out of luck. His lectures/lecture notes are just the textbook summarized and often contain errors in formulas. Even if you were to solve all textbook problems (as he recommends for outside study) you would not be prepared for his exams. He also does not plan to curve the course at this moment (I am still waiting for my grade). It is just appalling that this lazy professor managed to make a class which is normally regarded as one of the easiest math upper divs a complete nightmare.

I give him the same grade as the averages for our exams. An F. I don't think he was mean, just extremely incompetent. After our first midterm (the average was below 50%), he sent an email out saying that he wasn't sure what happened and that we needed to work harder. I don't think he could've gotten a passing grade on it. He pulled the most niche statistics dilemnas out of no where, because none of the stuff was in our textbooks. There is no assigned homework, so there's no feedback on how you're doing before you get railed by his tests.
Here is a summary of everything leading up to our impossible final:
1. He sends out an email a few days before saying that he realizes his lecture notes are incorrect and that we need to correct them via the book. He didn't bother correcting his pdf notes, but just threw it on us last second. It was wonderful trying to go through all of our notes for the quarter fixing over 10 significant mistakes (was completely copying down formulas wrong).
2. He says in our last lecture that we can use devices and open book because the exam will be very difficult. Of course, everyone decides that they will use their devices and don't need to prep as much or invest in a physical book (since everyone had the pdf). Then, two days before the exam, he cancels the device policy and says nevermind, just bring your book. I luckily was able to scramble and find a book last second, but most everyone couldn't get one in time and had to just correct their notes in limited time (again, because they were from him and wrong).
3. We go in, and proceed to get several problems that had no information on how to solve from the book. A book written by statisticians did not have the resources to answer the questions. I genuinely think he was just proud of his advanced stats research and gave us problems he solved to flex on us.
So, summarizing, I give him an F. He seems like a lovely guy, just seemed completely oblivious to how a class should be run. This class should not have been the hardest math upper division I've taken by far, but he managed.

This class is markedly harder in non-COVID quarters, and it seems like students liked his teaching style much less in person.

Ozel lectures by literally copying and pasting textbook chapters onto a chalkboard. If you don’t understand what he is saying in class, you’re out of luck because you will find the exact same information in the textbook.

The first midterm and final were unfairly difficult. A significant portion of both exams hinged on either remembering some obscure, seemingly unimportant fact from the class or mastering the content from 170E. I feel like these kinds of questions are unfair because they test whether or not you remember some nuance (i.e. you just happened to review that nuance a couple of days before the exam) instead of your overall comprehension of the broad 170S topics. In contrast, the second midterm was bordering on offensively easy.

I know Ozel has good intentions, but he simply doesn’t do a great job teaching or testing.

ozel is the best. if you're considering taking this instead of stats 100b, DO IT. the content of the class is much more practical and applicable. ozel makes it easy to understand, his quizzes and exams are very fair. he's extremely helpful, offers a ton of office hours, and is very patient, friendly, and makes the material easy to understand. it was actually a pleasure taking this class, 10/10 experience

Ozel is the best. He is very nice and responds to emails quickly. There are 5 simple quizzes, 2 of which are dropped. 2 fair midterms, but he drops 1 of them in one of the grading schemes. Final slightly harder than midterms.

Awesome prof. Tests were long because of COVID but they were fair and tested material we learned. Everything was so clear and reasonable and sometimes funny- every topic was explained very well and each exam and some lectures had great LOTR and pop culture references. Just know calculus and your 170E/170A/Stats 100A material decently enough and you should be fine, just remember to do the not-assigned practice problems. (P.S. Take this instead of Stats 100B any day, it's the same material minus some linear algebra stuff but explained soooo much better. I took the first couple weeks of 100B and everyone kinda hated it.)