S Curves

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

I want to spread a value over a range of dates as an "S-Curve" with the
ability to skew the distribution. What is the best way of doing this, please?
 
You can try the Trend function. You will need the analysis tool pack. It will
perform a polynomial regression on a set of values.

HTH
 
TREND is a built-in worksheet function. (You don't need Analysis ToolPak to
use it.) To go beyond linear regression, you could use xdata^{1,2,3} as the
x-data range in TREND, array-entered using Control+Shift+Enter.

The Regression tool of the Analysis ToolPak will perform polynomial
regression if you use x, x^2, and x^3 values (adjacent columns on a
worksheet) as the X-range.

Or, construct an XY (Scatter) chart with some hypothetical Y values, and use
Add Trendline (polynomial of order 3) to get a smooth curve approximately
through the points.

- Mike

www.mikemiddleton.com
 
The adequacy of a polynomial approximation depends on what will be done
with it. While a polynomial may approximate the center quite well, an
"S Curve" usually refers to a bounded function with zero first
derivatives at +/- infinity, while a polynomial is unbounded with
infinite first derivatives at +/- infinity.

Jerry
 
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