>Psychtoolbox>Psychometric

[alpha,beta,thresh92] = FitWeibTAFC(inputs,nCorrect,nError,[alpha0],[beta0])

Maximum likelihood fit of a Weibull function to TAFC psychometric data.

Requires the optimization toolbox. Doesn’t work with Octave yet.

INPUTS:

inputs: Contains the input levels
nCorrect: Contains the number of yes responses at
the corresponding input inputs
nError: Contains the number of no responses at
the corresponding input inputs
alpha0: Initial guess for alpha (optional)
beta0: Initial guess for beta (optional)

OUTPUTS:

alpha Weibull alpha parameter
beta Weibull beta parameter
thresh92 92% percent correct threshold

See also: FitWeibAlphTAFC, FitWeibYN, FitCumNormYN, FitLogitYN

8/25/94 dhb, ccc Cleaned comments, return 92% correct threshold
2/5/97 dhb Check if fminu is not available.
Add slope test.
4/26/97 dhb Fix bug in threshold assignment
10/13/00 dhb Improve initial guess for alpha. Thanks to Duje Tadin
for identifying the need for this.
4/18/02 dhb Suppress warnings in calls to optimization toolbox.
3/5/05 dhb Update for optimization toolbox version 2.