I'm preparing to attend graduate school for political science here in Canada and I'm having something of a crisis. Midway through my degree program I chose to drop my first love (English) to focus on what I was more interested in professionally. I'm now completing a honours degree in political science and international relations. Thing is, I've lost much of my quantitative ability (not that I had much to begin with). I was able to do some differential calculus a couple years ago, but I fear I've forgotten much of what I knew how to do.
I've become fascinated with quantitative methodology and want to practice quantitative research in graduate school. I'm currently on track to study theory. So here's my question: If I want to be able to use quantitative methods in grad school (say negative binomial regression, for example) how much math should I know prior to entering? Multivariable calculus? Linear algebra? Differential equations? When it comes to eventual knowledge, the sky's the limit, but I'm immediately concerned with applied maths. Pardon any ignorance inherent in this post.