Liao was an incredibly frustrating professor. I don't know what the other reviewers are talking about, but his midterm is 100x harder than the practice midterm, as is the final from the practice final. This quarter he gave us the final from the previous quarter, which is a slightly better indicator of the difficulty of the exam but overall not helpful. He's one of those professors who teaches you problems one way and then expects you to know how to do them a different way that you never even covered in class.
He has an accent, but if you're used to hearing accented English, it shouldn't be a problem. He basically rewrites his online lecture notes verbatim on the board during lecture with maybe a few extra example problems thrown in. The homework problems are absolutely no indicator of the difficulty of the exam questions, even the "starred" ones.
I think part of the problem for me is that he doesn't teach the class with an aim towards what you "need to know," if that makes sense. He just gives you everything and it's up to you to pick out the formulas and such that are important. He also gives you no context for what you're actually trying to do. I took AP Stats in high school, and my professor would teach the class in terms of 'population' and 'sample,' so you kind of knew the difference between things intuitively. Liao doesn't even really use those terms.

Basically, if you can avoid taking him, do. If not, I would recommend trying to find a tutor or some sort of supplemental help.

Liao was actually a surprisingly good professor. The quarter I had to take Econ 41 I didn't have the option to go with Rojas that I wanted, so I was nervous about taking Liao since he had no reviews and I heard his accent is pretty tough.

Nevertheless, the class is incredibly straightforward. All lecture notes are posted online and he merely goes into them in more detail in class which is very helpful since you can study things you may not have understood in class at home and clarify things in his online notes during lecture. The midterm was very easy and covered only up to basic probability concepts such as independence and conditional probabilities. It's made super easy and I, like a lot of people, was able to get 100 on it. He also provides a significant time gap between the midterm and the last content covered on it. So you have a good 2 weeks to study for the midterm which was very generous.

Our class was a bit behind so he did end up rushing a bit at the end when we got to actual hypothesis testing and he was barely able to finish the last lecture materials on the very last day of class. Things really do pickup very quickly after the midterm. This makes it a bit hard, especially because you likely fall behind at least a bit while studying for the midterm itself but it's doable as long as you have a good TA (Alec was great during my quarter) and try not fall too behind.

The final, like the other guy said, was definitely hard. it was more than twice the length of the midterm in less than twice the time (30 questions on midterm, 80 on final). On the other hand, no you don't need a tutor as long as you can... you know... study? The content on the final is definitely harder than the midterm. DO NOT solely rely on his practice questions to study for the final!! While that's a good strategy for the midterm, it will NOT help you for the final as the content is much more difficult and is meant to put you in a huge time crunch. That being said, he told us he didn't expect anyone to finish the exam (nobody did) and thus you should take your time, do the easiest first, and try to be as accurate as possible before just bubbling randomly in the last minute or two. I studied as many textbook, practice problems (TA and prof), and past exams from other classes as I could to be familiar with any type of problem he could throw and ended up getting one of the highest scores. The final is curved VERY generously though so don't worry. Average score was about a 50% i think

Overall, surprisingly good professor. Definitely a nice guy who does care. His accent can be rough at times but honestly he explains things pretty well regardless.

his midterm was hella easy, got 30/30. Midterm was exactly like the practice midterm he gave with different number, but the problem comes when you take final. I just studied practice study guide for final as his midterm was just like the practice guide, and he also stated that the practice guide will be the good study guide for final exam but NO. His final exam was 10000x harder than the practice guide with so many advanced questions. well... good thing that he curves the grade but if you dont study with tutor which cost 50$/hour, dont expect to get 70+ in his final exam. GOOD LUCK AND HAVE FUCKIN FUJN