Data Analysis with R, Second Edition - Second Edition

Third Anscombe relationship

We already dug deeper into this relationship when we spoke of robust regression earlier in the chapter. We saw that a robust fit of this relationship more or less ignored the clear outlier. Indeed, the robust fit is almost identical to the non-robust linear fit after the outlier is removed.

On occasion, a data point that is an outlier in the y-axis but not the x-axis (like this one) doesn't influence the regression line much, meaning that its omission wouldn't cause a substantial change in the estimated intercept and coefficients.

A data point that is an outlier in the x-axis (or axes) is said to have high leverage. Sometimes, points with high leverage don't influence the regression line much, either. However, ...