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Outliers in a Scatter Diagram

An outlier in a scatter diagram is a data point which
is the maximum distance from the regression line.
If two data points are the same maximum distance
from the regression line, then they are both outliers.

The outliers are marked in each scatter diagram
that is created below.

Move the "size" slider to select a new sample size.
Move the "seed" slider to select a new set of data.

Check the box next to "Show Distances" to show line
segments that are perpendicular to the regression
line and extend from each data point to the regression
line. The lengths of these line segments are the
distances of the corresponding points to the regression
line. These distances are shown next to each point.

This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

Usually, finding the distance from each point to the
regression line is not necessary. One can decide
which points are outliers just by looking or by
comparing the distances to the regression line for
only a few of the points.

Updated November 13, 2013.

Created by David Gurney using GeoGebra