similar to: irtoys

A new version of irtoys is / will be available on CRAN. Two minor bugs have been fixed. One of these is more interesting: the previous code did not anticipate negative estimates for discriminations. What I did not know is that, unlike ICL or Bilog, ltm does not constrain discriminations to be positive. This means that it can be used to analyze bipolar data (think political sciences). There are

A new version of irtoys is / will be available on CRAN. Two minor bugs have been fixed. One of these is more interesting: the previous code did not anticipate negative estimates for discriminations. What I did not know is that, unlike ICL or Bilog, ltm does not constrain discriminations to be positive. This means that it can be used to analyze bipolar data (think political sciences). There are

An updated version of the package plink has been uploaded to CRAN. This is a major revision that now includes multidimensional models and methods. plink is a package for conducting unidimensional and multidimensional IRT-based test linking using separate calibration methods for multiple groups for single-format or mixed-format common items. The package supports sixteen IRT models and eleven

An updated version of the package plink has been uploaded to CRAN. This is a major revision that now includes multidimensional models and methods. plink is a package for conducting unidimensional and multidimensional IRT-based test linking using separate calibration methods for multiple groups for single-format or mixed-format common items. The package supports sixteen IRT models and eleven

Hello I have a small problem with filled contour plots. I'd like to plot point on top of that using points(). Trouble is, the x axis of the contour plot is modified to make room for the legend but points() is not aware of that. It could be easily tackled by using a linear transformation of x in points(), but does anyone know exactly *what* transformation? Kind regards Ivailo Partchev

The first version of the package plink has been uploaded to CRAN. plink is a package for conducting unidimensional IRT scaling and chain linking for multiple groups for single-format or mixed-format common items. The package supports eight IRT models and four calibration methods. Dichotomous Models: 1PL, 2PL, 3PL Polytomous Models: -Graded response model -Partial credit model -Generalized

The first version of the package plink has been uploaded to CRAN. plink is a package for conducting unidimensional IRT scaling and chain linking for multiple groups for single-format or mixed-format common items. The package supports eight IRT models and four calibration methods. Dichotomous Models: 1PL, 2PL, 3PL Polytomous Models: -Graded response model -Partial credit model -Generalized

Hello, my question is; for a specific item, how can I create a plot with both the empirical probability of correct response and the predicted probability as a function of the mean of the ability intervals (similar to a BILOG plot). Thank you -- View this message in context: http://r.789695.n4.nabble.com/IRT-ltm-function-plot-for-probabilities-tp2714881p2714881.html Sent from the R help mailing

In the near future I will release MiscPsycho, a package that contains various functions useful for applied psychometricians. I would like to include some data sets for distribution in the package, but have not created any of these on my own, but have used data distributed in other packages such as the LSAT data in the ltm package. Is it appropriate for me to distribute a data set in the package I

CRAN (and crantastic) updates this week New packages ------------ * bisectr (0.0.2) Maintainer: Winston Chang Author(s): Winston Chang <winston at stdout.org> License: GPL-2 http://crantastic.org/packages/bisectr Tools to find bad commits with git bisect * CUMP (1.0) Maintainer: Xuan Liu Author(s): Xuan Liu <liuxuan at bu.edu> and Qiong Yang <qyang at bu.edu>

Hi Xavier, the reason you observe this feature is that in the 'constraint' argument you should specify the values under the additive parameterization, i.e., when in the second column of the matrix supplied in 'constraint' you specify 2, then you need to provide the easiness parameters (not the difficulty parameters) in the third column. Check the Details section of ?tpm() and

I have the following item response theory (IRT) likelihood that I want to maximize w.r.t. to theta (student ability). L(\theta) = \prod(p(x)) Where p(x) is the 3-parameter logistic model when items are scored dichotomously (x_{ij} = 0 or 1) and p(x) is Muraki's generalized partial credit model when items are scored polytomously (x_{ij} = 0 \ldots J). Now, I wrote the following two functions

Hi Everybody, I have just been introduced to R and have used the ltm package for calibrating items under IRT. I have been able to get the item parameters using the fit function under different models. I am using the 2PL model. I have got the parameters for some 300 items from 15 different tests using the function fit. Now I need to automatically generate tests such that they have atleast a

Dear R-users, I'd like to announce the release of the new version of package 'ltm' (i.e., ltm_0.9-0 soon available from CRAN) for Item Response Theory analyses. This package provides a flexible framework for analyzing dichotomous and polytomous data under various IRT models. Furthermore, supporting functions for descriptive statistics, goodness-of-fit, ability estimation and

Dear R-users, I'd like to announce the release of the new version of package 'ltm' (i.e., ltm_0.9-0 soon available from CRAN) for Item Response Theory analyses. This package provides a flexible framework for analyzing dichotomous and polytomous data under various IRT models. Furthermore, supporting functions for descriptive statistics, goodness-of-fit, ability estimation and

The function factor.scores is used with package ltm and others to estimate IRT type scores for various models. It inherits objects of class grm, gpcm and a few others. What I would like to do is to use the factor.scores function, but feed it my own item parameters (from a bifactor model where the 2PL parameters are adjusted for the bifactor structure). Does anybody have an idea of how this might

Hello All, I have searched many help forums, message boards, etc. and I just can't apply the comments to what I need my program to do. I am running R 2.5.1 on an XP system, and my desire is to produce replicate datasets for a simulation study I am running. Essentially, I have sets of parameters (a's, b's, and c's) that define a function which produces a decimal value. This

I would like to open a console application from within R and then send input to the newly opened console. I can use the following to open the application ... setwd(path) system(paste(path,"icl.exe",sep="")) This allows me to type in what want, but I would like to do something like this setwd(path) system(paste(path,"icl.exe",sep=""),input=c("icl

else. Stuart =20 ----- Original Message -----=20 From: Ivailo Karamanolev=20 To: flac-dev at xiph.org=20 Sent: Wednesday, January 06, 2010 7:49 AM Subject: Re: [Flac-dev] FLAC C API / Visual Studio 2008 FILE* Issue I thought about this, and the MSVCRT mismatch also. What annoys me is = that I even tried compiling the library myself (with exactly the same = Visual Studio 2008 as my

Hello All, I was wondering how I can get the overall Pearson chi^2 test of model fit with its df and p value in the LTM package for the 2PL models. Thanks, -- Davood Tofighi Department of Psychology Arizona State University [[alternative HTML version deleted]]