So what's interesting here is we're not trying to construct a confidence interval for just the mean number of snaps for the dominant hand or the mean number of snaps for the non-dominant hand. We're constructing a 95% confidence interval for a mean difference. Now, you might say, wait, wait, wait. You know, I have two different samples here, and then this third sample is, or this third data is somehow constructed from these other two. But one way to think about it, this is matched pairs design. So in a matched pairs design, what you do is, for each participant, for each member in your sample, you will make them do the control and the treatment. So for example, you could do the control as how many they can do in the dominant hand in 10 seconds, and the treatment is how many they can do in the non-dominant hand.