STATS 100B with Prof Li (Jessica) is tough, but only because the course itself is tough. Jessica teaches very well in class and always stops midway to ask if anybody has questions. She also willingly and patiently answers every question she is posed to clarify some of the things that she teaches. Her tests are deceptively easy, but actually quite challenging indeed. She doesn't have finals, she has 3 midterms instead, with the 3rd midterm having double weightage. One good thing is that she sets 1 bonus question per exam that allow you to regain some points that you might have carelessly lost otherwise, which is great! The bonus questions are challenging, but they do not cover material that she did not go through in class, so they are doable to a degree, as long as you complete the rest of the tests quickly enough. She gives 1 homework every week all of which are very manageable and she does not give homeworks during weeks when we have midterms. Also, she's very willing to help out with questions posed on CCLE or during her office hours.