MATLAB: Gaussian psychometric curve fit to the data

gaussian

Here is the problem I am working on; this should use erfc x = 1:5; y = [0.97 0.89 0.5 0.08 0.03]; we need to get slope and bias (The bias should be close to 3 and slope should be close to 0.78 for this) I need to use cumulative gaussian anonymous function f(x) = 1/2*erf( (

Best Answer

This works:
x = 1:5; 
y = [0.97 0.89 0.5 0.08 0.03];
f = @(p,x) 1/2 * erfc ( (x - p(1)) ./ (p(2).*sqrt(2)) );
P = fminsearch(@(p) norm(y - f(p,x)), [1; 1]);
Bias = P(1)
Slope = P(2)
Bias =
    2.9815
Slope =
    0.7784
Related Question