>Psychtoolbox>Psychometric

[alpha,beta,thresh50]=FitWeibYN(inputs,nYes,nNo,[alpha0],[beta0],[numFunCalls])

Fits a Weibull function to the passed yes-no data.

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

INPUTS:

inputs Input levels
nYes Number of yes responses at
the corresponding input inputs
nNo Number of no responses at
the corresponding input inputs
alpha0 Initial guess for alpha (optional)
beta0 Initial guess for beta (optional)
OUTPUTS:
alpha
beta
thresh50 50% threshold

See also: FitWeibTAFC, FitFitWeibAlphTAFC, FitCumNormYN, FitLogitYN

9/15/93 jms Added a pre-fit to get a better initial.
jms Made ‘options’ a parameter so that printing could
be disabled higher up.
9/23/93 jms Test the slope of the linear pre-fit to set the upper
and lower bounds on the fit.
2/5/97 dhb Rewrote to parallel TAFC version but kept slope test.
dhb Check for optimization toolbox.
4/18/00 mpr Added an option to set the number of allowed function calls
10/13/00 dhb Improve initial guess for alpha. Thanks to Duje Tadin
for identifying the need for this.
3/5/05 dhb Update for optimization toolbox version 2.