Applet Exercise Access the applet Removing Points from

Chapter 11, Problem 108SE

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Problem 108SE

Applet Exercise Access the applet Removing Points from Regression. Sometimes removing a point from those used to fit a regression model produces a fitted model substantially different that the one obtained using all of the data (such a point is called a high-influence point).

a The top graph gives a data set and fitted regression line useful for predicting a student’s weight given his or her height. Click on any data points to remove them and refit the regression model. Can you find a high influence data point in this data set?

b Scroll down to the second graph that relates quantitative SAT score to high school rank. Does the slope of the fitted regression line surprise you? Can you find a high-influence data point? Does removing that data point produce a regression line that better meets your expectation regarding the relationship between quantitative SAT scores and class rank?

c Scroll down to the remainder of the data sets and explore what happens when different data points are removed.