Overall, my suggestion is to avoid this class (Time Series Analysis) if your intention is to learn useful knowledge and not to waste your tuition. Prof. Safikhani is a generous curver but not so generous as a teacher/professor. He constantly cancelled his office hours due to "conferences", which happened at 7:40 at night? His substitute had no idea what he was talking about and he was not even able to read the PowerPoint proper. Prof. Safikhani asserted that he would not answer any homework questions and would left those to the TAs. Unfortunately, we had appalling lady this semester as our TA, who possessed a hateful attitude towards students in this class. So you really should have a solution to do the HW problems, some of which were never covered in class.
It is not surprising that the STAT department is packed with irresponsible faculties. Prof. Safikhani is not the worst, but nor could he be called a good professor. His lecture is wishy-washy and offers no insights to the textbook - in fact, it is just a simplified version of the textbook. He is not able to explain essential proofs. The class is very dull.
That said, he is a generous curver - he said he would curve the average to an A-. So if your ultimate goal is for a facade of good grades, he should definitely be in your consideration. Yet, I would say such a grade means nothing more than a letter. At the end of the day, you, as a student, are left confused, helpless and disappointed, having paid so much for a useless class with unhelpful TAs and faculty.
So save your money and stay away from this.