Grapher and Excel report the same R2 value except when a through-origin fit is being used.
- Grapher uses an equation specifically designed for a through origin fit that accounts for how the line is centered.
- Excel uses the same equation even if the fit curve is forced through the origin. This results in a different R-squared value in Excel. This value can sometimes be negative, so using the same equation is not a good idea when forcing a curve through the origin.
Refer to the Fit Statistics Grapher help page for the R-squared equation used in both cases (through-origin and not through-origin).
Updated April 2023