| ConQuest - Generalized Item Response Modeling |
Margaret L. Wu, Raymond J. Adams, Mark R.
Wilson and Sam Haldane
ConQuest Version 2.0 is a computer program for fitting item
response (Rasch) and latent regression models. It provides a
comprehensive and flexible range of item response models (IRM) to
analysts, allowing them to examine the properties of performance assessments, traditional
assessments and rating scales. ConQuest 2.0 also offers the wider measurement and
research community the most up-to-date psychometric methods of multifaceted item
response models, multidimensional item response models, latent regression models and
drawing plausible values.
ConQuest Version 2.0 Enhancements
ConQuest Version 2.0 has incorporated many enhancements to the 1998 release.
These include:
- plots of item characteristic curves
- user-defined fit statistics
- estimation of population characteristics such as percentages above a cut-point on a scale,
- more user-friendly interface
Models ConQuest Can Fit
- Raschs Simple Logistic Model
- Rating Scale Model
- Partial Credit Model
- Ordered Partition Model
- Linear Logistic Test Model
- Multifaceted Models
- Generalized Unidimensional Models
- Multidimensional Item Response Models
- Latent Regression Models
How Does ConQuest Fit These Models?
ConQuest produces marginal maximum likelihood estimates for
the parameters of the models. The estimation algorithms it uses
are adaptations of the quadrature method described by Bock and
Allen (1981) and the Monte Carlo method of Volodin and Adams
(1995). The fit of the models is ascertained by generalizations
of the Wright and Masters (1982) residual-based methods developed
by Wu (1997). The manual contains a summary of these procedures.
Some Applications of ConQuest
- Performing item analysis
- Examining differential item functioning
- Exploring rater effects
- Estimating latent correlations and testing dimensionality
- Drawing plausible values
ConQuest is available with both a graphical user interface
(GUI) and a simple command line, or console, interface. The
console version of the program is available for all of the
ConQuest platforms except Windows 3.1x. The GUI version is
available for all Windows platforms.
Program Limits
- Item response categories: 65
- Item codes: 200
- Number of generalised items for each case: 1000
- Response model parameters: 3000
- Latent dimensions: 15
- Elements in each facet: 1000
- Characters in a line of data and length of filename path: 3072
- Lines specified in a formal statement: 20
- Variables in a model statement: 1000
- The number of item steps is not limited except by system memory.
Comparing ConQuest and Quest
Quest fits Raschs simple logistic model (for sets of
dichotomously scored items), Andrichs Rating Scale Model
(for analyzing Likert scales) and Masters Partial Credit
Model (for analyzing polytomous items or mixtures of dichotomous
and polytomous items). Quest also implements Mantel-Haenszel
approaches to assess differential item functioning. ConQuest can
fit a wider range of item response models than Quest. ConQuest
can also fit both unidimensional and multidimensional latent
regression models. Quest uses joint maximum likelihood to
estimate parameters, whereas ConQuest uses marginal maximum
likelihood. Quest is available for Macintosh OS, DOS, Windows 95
and Windows NT, but it does not have a GUI interface. ConQuest is
available for Windows and Windows NT with a GUI interface and a
console interface.
Books on Rasch Models and Related Methods
System Requirements
Windows 95, 98, NT, ME, 2000, XP, Vista*
* Vista installation requires running installer as administrator.
ConQuest PDF Manual
ConQuest 30 Day Trial Copy
This is a time-limited, fully functioning copy of ConQuest 2.0 for Windows. If you decide to purchase ConQuest 2.0, just e-mail or fax us the unlock codes and payment information. As soon as you receive our reply, you can unlock the software already on your computer without having to reinstall ConQuest 2.0. This download includes the complete 200+ page PDF manual.
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