Same thing as the population mean. And its variance, so the variance over here, so the variance for the sample means, or the standard error of the mean, actually this isn't the standard error. This is the, I guess you could, well, standard error would be the square root of this. So if I call this the standard error mean, that's wrong. The standard error of the mean is the square root of this. It's the standard deviation. This is the variance of the mean.