I am attempting to fit a nonlinear curve to the data listed below using Excel
2003 with the standard stat add-in provided with Excel. I normally use SAS
for statistical analysis and am not familiar with all the capabilities of
Solver, etc. I would like to achieve the above curve fit solution using
Excel, since this is one step in an application to be used by others who do
not have SAS, but have basic Excel capability. In SAS I fit a nonlinear
regression curve of the form: lnY1 = b * exp( -a*lnX1), this provided
coefficients of b=-1.91 and a=0.515, with an R-square of 0.98 (not perfect
but close enough !). I have not been able to duplicate this in Excel. The
closest I can come (without expensive 3rd-party add in software), is to fit a
logarithmic curve (chart,trendline, etc) and this doesn't handle the limit
approached on the Y-axis very well. Any ideas ? (heres the data in its
original, non-Ln transformed format):
X Y
0.09 0.00123
0.15 0.0067
0.2 0.0137
0.4 0.0494
0.6 0.0852
0.8 0.1176
1 0.1465
1.2 0.1724
1.4 0.1957
1.6 0.2168
1.8 0.2361
2 0.2539
5 0.4193
10 0.5437
20 0.6544
40 0.7453
60 0.7888
80 0.8156
100 0.8343
500 0.9748
700 0.9787
1000 0.9822

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Thanks
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geocalc