So this is negative 1.96 times the standard deviation of this distribution. And if there's a 95% chance, so let's put it this way. There's a 95% chance that our mean, or I guess we could say that our sample that we got from our distribution, this sample is a difference of these other samples. There's a 95% chance that 1.91 lies within, or let me just write, is within this distance is within 1.96 times the standard deviation of that distribution. So you could view it as a standard error of this statistic. So x1 minus x2. Or we can say that there is a 95% chance that 1.91, which is the sample statistic or the statistic that we got, is within 1.96 times the standard deviation of this distribution of the mean of the distribution, of the true mean of the distribution.