Mean of 0, and then a variance of 1, which would also mean, of course, a standard deviation of 1. So that could be the standard deviation, or the variance, or the standard deviation, that would be equal to 1. So a chi-squared distribution, if you just take one of these random variables, and let me define it this way. Let me define a new random variable, q, that is equal to you essentially sampling from this standard normal distribution, and then squaring whatever number you got. So it is equal to this random variable X squared. The distribution for this random variable right here is going to be an example of the chi-squared distribution. Actually, what we're going to see in this video is that the chi-squared distribution is actually a set of distributions, depending on how many sums you have.