And you could if you were able to say, well, I could take the difference between my sample mean and the assumed mean in the null hypothesis. So that would be this right over here. That's what that zero means, the assumed mean from the null hypothesis. And I would then divide by the standard error of the mean, which is another way of saying the standard deviation of the sampling distribution of the sample mean. But this is not so easy to figure out. In order to figure out this, this is going to be the standard deviation of the underlying population divided by the square root of N. We know what N is going to be if we conducted the sample, but we don't know what the standard deviation is. So instead, what we do is we estimate this.