Gaussian psychometric curve fit to the data

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Janani Thiyagarajan 2017-11-14

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https://ww2.mathworks.cn/matlabcentral/answers/367043-gaussian-psychometric-curve-fit-to-the-data

评论： Star Strider 2017-11-14

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( (

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Star Strider 2017-11-14

在 MATLAB Online 中打开

Please complete your Question:

f(x) = 1/2*erf( ( ???

What parameters do you want to estimate?

Janani Thiyagarajan 2017-11-14

Here is the complete question; it got truncated due to symbols usage 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 ( (x - bias) / (slope*sqrt(2)) )

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Answer 1

Star Strider 2017-11-14

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https://ww2.mathworks.cn/matlabcentral/answers/367043-gaussian-psychometric-curve-fit-to-the-data#answer_291128

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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