That tells you all of the possibilities. In real life, we seldom know all of the possibilities. In fact, in real life, we seldom know the pure probability generating function, only if we're kind of writing it or if we're writing a computer program. Normally, we're doing samples and we're trying to estimate things. So normally, there's some random variable and then maybe we'll do a bunch of... We take a bunch of samples, we take their means and we plot them and then we're going to get some type of normal distribution. Let's say we take samples of 100 and we average them. We're going to get some normal distribution.