Trendline Equation error Excel 2007?

[Guest]

I made a scatter chart of some data in Excel 2007 and placed a power fit
trendline that resulted in the equation y=0.075x^-0.06 with a R^2 of 0.983.
If I try to back calculate data points based on this model I get values that
differ from the input data. I took the exact same data in Excel 2003 and I
get a different equation (y=0.1001x^-0.0572) and R^2 (0.9931). I used this
equation to back calculate some input values and it worked perfect. Is there
an error with the equation reporting routine in Excel 2007? My OS is XP HOME
SPII



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[Jon Peltier]

Make sure in both cases you use an XY chart, not a line chart. Also, expand
the number format of the regression formula to display as many digits as
possible, using a scientific format with lots of decimal places,

- Jon

 

[Bernard Liengme]

If you still have problems, send me the file (not to newsgroup but to
private email)
I would like to check this out.

 

[John]

Did anyone find out anything about this problem with Excel 2007?

I did a similar power trend line and got the formula y = 14371x^-.025 with
R^2=0.978. The results from that formula plotted on the graph were no where
near the trend line drawn on the graph.

I modified the formula to y = 13200x^-0.25 and the plotted graph is now
superimposed on the trend line.

Thanks,

John