[R] psychometric functions

[Mario Maiworm]

Thank you harold. Hmm thats bad news. I will have a look at the LTM package
but right now I feel like I should lean back and use matlab, and then get
the fit results into R for further analyses...
mario


__________________________________________________________________

Mario Maiworm
Biological Psychology and Neuropsychology
University of Hamburg
Von-Melle-Park 11
D-20146 Hamburg

Phone: +49 40 42838 8265
Fax: +49 40 42838 6591

http://bpn.uni-hamburg.de/Maiworm_e.html
http://cinacs.org
__________________________________________________________________

>>> -----Original Message-----
>>> From: Doran, Harold [mailto:HDoran at air.org]
>>> Sent: Thursday, August 21, 2008 2:40 PM
>>> To: Mario Maiworm; r-help at r-project.org
>>> Subject: RE: [R] psychometric functions
>>> 
>>> I am pretty certain a function for this model does not exist. Jan
>>> Deleeuw or Dimitris Rizopolous may suggest otherwise. There is a
>>> package
>>> for a model that would allow for the lower asymptote of the function
>>> to
>>> be > 0; it does not however, allow the upper asymptote to vary from 1
>>> (well, it tends to 1) and this is in the ltm package.
>>> 
>>> 
>>> > -----Original Message-----
>>> > From: r-help-bounces at r-project.org
>>> > [mailto:r-help-bounces at r-project.org] On Behalf Of Mario Maiworm
>>> > Sent: Thursday, August 21, 2008 7:05 AM
>>> > To: r-help at r-project.org
>>> > Subject: [R] psychometric functions
>>> >
>>> > Hi,
>>> > I want to fit some psychophysical data with cumulative
>>> > gaussians. There is quite a convenient toolbox for matlab
>>> > called 'psignifit' (formerly known as 'psychofit'). It allows
>>> > the lower bound of the sigmoid to vary slightly from zero,
>>> > aswell as the upper bound to vary from one. with these two
>>> > free parameters, the fitted function is less sensitive to
>>> > noisy data and outliers.
>>> > Apart from advertising this toolbox I want to ask for
>>> > possibilities in R to fit psychometric functions, as I would
>>> > rather use R than matlab. Is there a comparable package
>>> > specific for psychophysics in R? otherwise: which function
>>> > would be a good choice? Can I have functionality equal to
>>> > 'psignifit' with glm() from MASS. I would be grateful for
>>> > some suggestions of people who have experience in
>>> > sigmoid-fitting in R.
>>> > Best,
>>> > Mario.
>>> >
>>> >
>>> > __________________________________________________________________
>>> >
>>> > Mario Maiworm
>>> > Biological Psychology and Neuropsychology University of
>>> > Hamburg Von-Melle-Park 11
>>> > D-20146 Hamburg
>>> >
>>> > Phone: +49 40 42838 8265
>>> > Fax: +49 40 42838 6591
>>> >
>>> > http://bpn.uni-hamburg.de/Maiworm_e.html
>>> > http://cinacs.org
>>> >
>>> > ______________________________________________
>>> > R-help at r-project.org mailing list
>>> > https://stat.ethz.ch/mailman/listinfo/r-help
>>> > PLEASE do read the posting guide
>>> > http://www.R-project.org/posting-guide.html
>>> > and provide commented, minimal, self-contained, reproducible code.
>>> >