hi, is there a way to estimate the parameters of an IRT model (in my case, the graded response model), when some item parameter are already known? what i have heard is that other irt programs such as parscale allow to prespecify some of the item difficulty and location parameters and estimate only the unconstrained parameters.
i usually use ltm for model estimation. best, felix Dr. rer. nat. Felix Fischer Diplom-Psychologe Institut für Sozialmedizin, Epidemiologie und Gesundheitsökonomie Charité - Universitätsmedizin Berlin Luisenstrasse 57 10117 Berlin Tel: 030 450 529 104 Fax: 030 450 529 902 http://epidemiologie.charite.de ______________________________________________ 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.
