Which statement about influential points is true?
I. Removal of an influential point changes the regression line.
II. Data points that are outliers in the horizontal direction are more likely to be influential than points that are outliers in the vertical direction.
III. Influential points have large residuals.
A) I only
B) II and III
C) I and II
D) I, II, and III
E) I and III

Question

Quizplus · Accepted Answer

I is true because influential points, by definition, have a significant impact on the slope and intercept of the regression line, so removing them would change the regression equation. II is also true because outliers in the horizontal direction (leverage points) can have a more significant impact on the slope of the regression line than outliers in the vertical direction. III is incorrect because influential points do not necessarily have large residuals; their influence is more about their position relative to the other data points and how they affect the slope of the regression line, not just the size of their residual.

Which Statement About Influential Points Is True