Okay, we’re doing math now, so let’s start with something super simple; a vector. Oh my gosh you’re thinking, a vector dah, I’ve seen this a million times. Well, I just want to remind you that there are a couple of different ways of thinking about a vector, that we will transition between when discussing analysis methods. First, a vector is a collection of numbers, as in you might make a bunch of measurements and put them into a column in a spreadsheet application and think of that as a vector. For example, you could think of the returns of several companies stocks on the same day as a vector. But the other way to think of a vector, which you may also be familiar with, is as a direction in space. Remember like a 3 D vector is also an arrow pointing from the origin to a point in 3 D space. These are both valid views and we’ll need both to get to where we’re going. I want you to be comfortable with the idea that we’ll need to switch back and forth between them, as we move through this content.