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:[EMAIL PROTECTED] >>> Sent: Thursday, August 21, 2008 2:40 PM >>> To: Mario Maiworm; r-help@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: [EMAIL PROTECTED] >>> > [mailto:[EMAIL PROTECTED] On Behalf Of Mario Maiworm >>> > Sent: Thursday, August 21, 2008 7:05 AM >>> > To: r-help@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@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. >>> > ______________________________________________ R-help@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.
