Hi,

I am having an issue with the polynomial trendline equation generated by Excel 2007. Data consists of 2C x 64R, so I am trying to fit a second order polynomial equation for first column vs second column in an XY scatter plot. The polynomial equation should intercept at (0,0), so I set intercept at zero. I get an R^2 of 0.9998, so the equation fits pretty well. But the equation is not fitting the actual data as well for earlier values close to x=0, but fits very well for higher values, ie the percentage error between data points and trendline equation is very high for the first point (~800%) but after the first 15 points, error in the data array comes down to 1%. But I need high accuracy for the entire set. Is this a known issue with Excel or am I missing something?

--
Best Regards
quanto