AS/A2 Stats 2 Stats 3

S1 Topic 4: Correlation and regression
Restricting the range
This Java applet shows how the correlation between two variables is affected by the range of the variable plotted on the X-axis. When the applet begins, the dataset "Assumptions met" is plotted in both the upper and lower graphs. For these data, the relationship between X and Y is linear. The following statistics are computed for each graph: N the number of points slope the regression slope r Pearson's correlation sd of est. the standard error of the estimate The lower graph also shows r(c), Pearson's correlation corrected for restriction of range. The upper graph has two vertical bars that can be moved with the mouse. You can use these bars to select a range of points to be included in the lower graph. The radio buttons located between the graphs allow you to specify whether to include the points inside the bars or outside the bars. The lower graph and its associated statistics are based on only the subset of the data specified.

an applet from the Rice Virtual Lab in Statistics