I need to fit a curve like the one in the following picture:
I think this is done with the statistical toolbox in matlab. I tried cure fitting in mathcad but i think it works here. I will attach my mathcad file. Can anyone check and see if the problem is with the low number of points or the one in the picture is using something different from curve fitting.
Why do you think that a polynomial of order 4 or a logistic curve would provide a good fit?
Here are two examples using a Rational Model and a Gaussian:
The success of curve fitting depends greatly on a good guess which type of function might fit best. Then you can use a software like Mathcad to calculate the best parameters for this type of function.
In case of real data you might know which mathematical function is appropriate for the process the data stems from.