 Hi, this is Dr. Don. I have another problem at a Chapter 9 of Regression, and this one we're asked to determine whether or not we have possible outwires and influential points in our data, and we can do this very quickly using StatCrunch. I'm going to click on the little rectangle, open the data in StatCrunch, and then we're going to go to Stat, Regression, Linear. We want to select our X variable, and they tell us X, and our response variable Y, and we want to get the fitted line plot, and we click on Compute, and we have a regression that is significant, because the p-value is less than 0.05, and we have our slope and intercept. Let's look at the line plot. If you look at the scatter plot there, you can see we have our main grouping of data points up here to the left, but we have this point way down here that's isolated, so that would tend to make you think it could be an outlier, and in another part of the course we'll talk about how to do precise calculations to determine if it's an outlier, but in this case we can just say that's possibly an outlier, but is it an influential point? Does it really matter that it's out there? Well, here's how we're going to do that. We have the calculations here with that data point, and we're going to run it again without that data point. I'm going to select these two columns in the data, highlight those, and you need to use the Ctrl C to copy. I'm going to click in that column, and use the Ctrl V Victor to paste. I'm going to rename those x2, y2 so I can tell them apart, and then I'm going to get rid of this point down here that I think may be influential. Now we're going to go back to stat, regression, simple linear. Again, I'm going to select my x, select, whoops, my y2, let me go back, and select x2, make sure I've got the fitted line pot, click compute, and here we've got a second set of data. Let me make some room here, and you can see that the intercept doesn't really change a whole lot, and the slope is still negative, and it doesn't change a whole lot. If we look at our slope, our scatter plot, you can see that that scatter plot is pretty close to the same, so in my judgment, and of course this is subjective, I would say that point is not influential.