Thanks for responding.

I plotted an XY scatter chart, setting the intercept to 0 and displaying the
R-squared value. I was surprised to see that the R-squared value I obtained
from SAS was different. So I went back to Excel, did "Regression" under Tools
> Data Analysis, set the intercept to 0 also, and the R-squared value was the
same as the value I obtained from SAS.

I thought that maybe there was something wrong with my data, so I made up
some X and Y values and did the same comparison. And indeed, both methods in
Excel give different values.

r505el


"Jerry W. Lewis" wrote:

> Not enough information. What kind of chart?
>
> If the chart is an "XY (Scatter)" chart, then mathematically there is no
> difference between the R-squared calculated by linear chart trendline, the
> ATP Regression tool, LINEST (fitting a straight line) or the RSQ worksheet
> function. Numerically, there may be a difference in Excel versions prior to
> 2003 because the algorithms used by ATP, LINEST, and RSQ did not use the
> available numeric accuracy as efficiently as did the chart trendline.
>
> If the chart is a "Line" chart, then both the R-squared and the trendline
> estimated by the chart assume that predictor (x) values are 1,2,3,... even if
> you specified different values.
>
> Jerry
>
> "r505el" wrote:
>
> > What is the difference between (1) the R-squared value generated when you add
> > a linear trendline on a chart and (2) the R-squared value generated when you
> > do regression in the Data Analysis add-in?