Need help to plot logistic curve in Microsoft Excel

[GuruT]

I need to fit a logistic curve to data points on a scatter plot to determine if regression (r^2) values are closer to 1, then linear or exponential regression lines. The formula is Y = N/1+Ab^-t where N = 281422, A = 281421, b = %increase/time (slope), and t = time (x axis) my data points are as follows: (0,38558),(10,49371),(20,62980),(30,76212),(40,922 28),(50,106022),(60,123203),(70,132165),(80,151326 ),(90,179323),(100,203212),(110,226546),(120,24871 0),(130,281422) examples are greatly appreciated.

[Alfons]

I am a little bit confused. What is the value of b. Are the pairs (t,Y). Is t in seconds or minutes. Use Linest, Logest, or Trend. These are worksheet function that you can put on you worksheet or call the from VBA.

• worksheetfunctions.Linest(Parm1, Parm2, Parm3)
• worksheetfunctions.Logest(Parm1, Parm2, Parm3)
• worksheetfunctions.Trend(Parm1, Parm2, Parm3)
• =Linest(Parm1, Parm2, Parm3)
• =Logest(Parm1, Parm2, Parm3)
• =Trend(Parm1, Parm2, Parm3)

See worksheet help for more details. In VBA use Range("A14") for Params.

[Gania]

If you want to fit a logistic curve to some data, you have to create the graphic, choose Scatter diagram. Once you got the graphic, you have to press the right button on the graphic, choose to adjust trend line. There is a tab where you can choose which type of trend line need. You have to choose logistics. Luck. I hope I was clear.