It is really unfortunate that this class is most students first introduction to the field of epidemiology. While Professor Olsen may be a genius in the field, his teaching skills are nearly non-existent. After being in his class for more than a quarter, I feel that most students know little more than when we all began. His lectures are unclear and boring- he really might as well be speaking in another language. He seems much more concerned with the grade distribution than whether or not his student actually understand a single thing that's going on.
Your best bet to do well in this class is to not listen in lecture (seriously, it will only confuse you more), and study the TA handouts, as well as online resources (google, wikipedia, journal articles, whatever you can find). My next piece of advice would be to just do the best you can, and stick it out- fortunately the 200 series in just one year- then you can move on to electives that will teach you way more about the field.
This is an extremely disappointing class, but I would suggest, to minimize YOUR feelings of disappoint, to not expect to learn anything from Professor Olsen. Because you probably won't.

Not a fan at ALL. He may be an Epi genius but he is a terrible teacher. First of all he has a strange dutch accent that is difficult to understand, second he mumbles like he has peanut butter stuck in his mouth and he his superbly dull. Tests are difficult and when you get your test back he doesn't actually tell you what questions you got wrong, you basically get an overall grade. He basically does this because he doesn't want you to be able to argue for extra points. How can you if you don't know what you got marked down for? He did this for both the midterm and the final. The only way I survived was by having a great T.A. and a really smart friend in my class. He is terrible at explaining concepts and though he gives you PPT slides they are covered with more or less gibberish and the textbook is horrible too so don't count on it to help clear things up. I will say however, that he is available to meet with during his office hours though when I did go see him, his explanations were not much better than the first time around. Luckily he is a pretty generous curver, Im pretty sure I should have gotten a C- but I ended up with a B+. Good luck!