And he takes seven of those days. So n is equal to seven. And from that, he calculates sample statistics. He calculates the sample mean, which is trying to estimate the true population mean right over here. And he also is able to calculate a sample standard deviation. And what you do in a significance test is you say, well, what is the probability of getting this sample mean or something even more extreme, assuming the null hypothesis? And if that probability is below a preset threshold, then you would reject the null hypothesis, and it would suggest the alternative.