
[Analyze][Convert Data]
[special][subtract line]
This item is enabled after you carry out [Analyze][Fit Regression Line] and/or [Fit Manual Line]. Then you have a graph like this.
You can subtract the y value of a line from the data poins using its slope and intersection. The "Select line" window opens by clicking the "subtract line" button.
Then you simply select a line to use by the corresponding radiobutton. You can also edit numbers if you do not like the result of fitting. After pressing the "OK" buttons on the "Subtract line" and "Convert data" windows, you will have a graph like below.
