If you add an exponential trendline in an Excel (x,y) scatterline diagram, the displayed
R² value is not the correct one!Excel instead displays the R² of the linear approximation line for the (x,ln[y]) scatterline diagram.
Everyone can check this out: calculate the R² yourself with the appropriate Excel function (determination coefficient), and you will see that it is different from the one in the diagram (at least in general).
The same type of error occurs for potencial trendlines.