To make the correlation coefficient r appear from now on, follow these steps:

(You do not need to press ALPHA)

Select the command DiagnosticOn.

...

You only need to perform this step once. The value of r will be displayed unless your defaults or your memory is reset.

To prevent r from being displayed, do the following:

(You do not need to press ALPHA)

Select the command DiagnosticOff.

...

You only need to perform this step once. The value of r will not be displayed from now on.