Assessment Systems Corporation :: Software :: Item Response Theory :: Xcalibre 4 - Software for IRT analysis and calibration

Xcalibre 4 - Software for IRT analysis and calibration

Customer Testimonial

This is the easiest IRT software package to use ever created! ASC has bundled into one application that which took several applications to do in the past. Contained in one Windows tabbed interface, you can define your working files, input format, IRT model, calibration requirements, estimation methods, and output options. A full range of dichotomous and polytomous models are easily selected, calibrated, scaled to your theta estimation method, and outputted to highly useful graphs and tables in rtf and csv formats. This truly represents a high benchmark in the state of the art for IRT analysis.

Cliff Donath, The Donath Group

Xcalibre™ 4 represents the leading edge in software for item response theory (IRT) analysis of assessment data. Xcalibre™ 4 calibrates your test using 4 dichotomous and 5 polytomous IRT models, and produces professional reports summarizing the analysis, complete with embedded graphics and tables to facilitate data interpretation. Xcalibre™ 4 is the most user-friendly comprehensive IRT software available; no more DOS command code!

Xcalibre 4 offers several substantial advantages over Xcalibre 1.1:

1. Superior output: save time by utilizing the rich text file (RTF) format prepared as a formal report with embedded tables and graphics, rather than having to build your own report manually. Graphics include the item response function (IRF), the item information function (IIF), the test information function (TIF), and conditional standard error of measurement (CSEM), and numerous frequency distributions. In addition, you can also overlay the empirical fit line with the IRF.
2. More models: Dichotomous models include the 3PL, 2PL, 1PL, and Rasch models. Five polytomous models (below) are also included, plus you are allowed to mix the models for mixed-format tests.
3. Screening: automatically screen out items with unacceptable classical statistics before performing the IRT item parameter calibration.
4. Custom flagging: customize item flagging rules by specifying acceptable ranges and your own flag labels.
5. Produces spreadsheets: easily import results into test development software because statistics are saved as a comma-separated value (CSV) format, which is also able to be easily manipulated (sorted, highlighted, etc.) in spreadsheet software.
6. More theta estimates: can now be produced for multiple domains as well as the full test.
7. Mastery testing: automatically implement cutscores for criterion-referenced tests.
8. More items: analyze up to 1,500 items at once.
9. Pilot/pretest items: compute classical statistics for pretest (pilot or unscored) items to be used for item evaluation.
10. Multiple runs (batch): utilize a “batch” type of capability, to allow you to run multiple data sets without having to use the graphic user interface for each run.
11. Differential item functioning (DIF): evaluate DIF with the Mantel-Haenszel approach.
12. Scoring-only functionality: score examinees using previously calibrated IRT parameters, for example with paper-based tests.

IRT Models

Xcalibre calibrates the following IRT models:
  • 3-parameter dichotomous model, ideal for multiple choice data
  • 2-parameter dichotomous model, ideal for personality data
  • 1-parameter dichotomous model, with equivalent item discriminations
  • Rasch dichotomous model, scaled to items rather than people
  • Rasch rating scale model (RRSM, or RSM)
  • Rasch partial credit model (RPCM, or PCM)
  • Generalized rating scale model (GRSM)
  • Generalized partial credit model (GPCM)
  • Samejima's Graded response model (SGRM, or GRM)
Moreover, you are allowed to utilize both a dichotomous and polytomous model at once. For example, if your test has 100 multiple choice questions and 5 open response questions scored with partial credit, you can calibrate all items easily onto a common scale. Because no programming code is involved (point-and-click only), even researchers new to IRT can easily produce such powerful analyses.

Using Xcalibre 4

Xcalibre 4 is designed to be user-friendly, with a straightforward graphical user interface that involves no DOS-style command code. All options are specified by radio buttons and check boxes; once you have all of your specifications set, simply hit the "Run" button!

Xcalibre 4 produces top-of-the-line reports designed to make it easier to apply IRT. Instead of oversimplified ASCII-text files, it produces a detailed document with colored headings, embedded figures and tables, and explanations. All statistics are also saved as a CSV file to allow you to work in a spreadsheet and easily upload to test development systems such as FastTEST Web ( In addition to the detailed page show below, which is produced for every test item, Xcalibre 4 provides a wide range of test-level output for the overall test as well as each domain (content area):
  • Test information function (TIF)
  • Conditional standard error of measurement (CSEM)
  • Test response function (TRF)
  • Grouped frequency distributions of theta estimates
  • Coefficient alpha
  • Summary statistics of item parameters, raw scores, and theta estimates.
  • Overall grouped frequency distributions of item parameters

The marginal maximum likelihood (MML) algorithm utilized in previous versions of Xcalibre has been enhanced to be even more accurate. The following table presents the parameter recovery results of a monte carlo simulation study, where item responses were generated for 1,000 simulees based on known item parameters for 100 items. A full monte carlo parameter recovery study is available here, while a comparison of Xcalibre's accuracy with other software is available here.

Parameter and Statistic Xcalibre 1.6 Xcalibre 4.1.7
a Parameter
Average Signed Difference 0.00 -0.02
Average Absolute Difference 0.07 0.07
b Parameter
Average Signed Difference -0.09 -0.02
Average Absolute Difference 0.11 0.09
c Parameter
Average Signed Difference -0.02 -0.01
Average Absolute Difference 0.03 0.02


Xcalibre 4 licenses are determined by the use of the program:

Student research license - Grants are provided to cover costs of our software, allowing students to purchase a full academic license; click here for more information and an application.. Note that the demo version (downloaded below) can also be used as a free student version.
Academic ($495 per year, or $990 for 3 years) - The program will be used at an accredited college or university for research or teaching purposes only.
Government ($995 per year, or $1990 for 3 years) - The program will be used at a governmental organization, or by a school district or college or university for analyzing the data from its testing programs.
Commercial or Non-profit (contact us for price) - Please let us know how you intend to use the software.
Upgrades - For upgrades from version 1.1 licenses (2010 or earlier), you will receive $100 credit towards the new version (4.2). Please order the appropriate license below and then contact us with information regarding the previous purchase, so we can validate the existing license. For upgrades from version 4.0, the cost is $100; contact us to order. The upgrade credit is available for customers with previous Xcalibre licenses or the Item and Test Analysis Package. This is on an individual license basis: one previous license provides one discount on one new license.


Initial support is provided by the detailed manual that is included with the software. Additionally, we have provided free training videos here. Please check the manual and videos before contacting us; in-person support for Xcalibre 4 is available at our normal consultant billing rates.

Purchasing Xcalibre 4

Xcalibre 4 is available via download from the link below. It includes all the same files that would be sent on a physical CD, so CD shipping is not necessary. If you wish, you are free put the ZIP file onto a CD or USB drive as a backup, which saves expensive shipping costs if ASC were to produce a CD and send it to you.

Xcalibre 4 is downloaded as a demonstration version limited to 50 items and 50 examinees. This allows you to get familiar with the program immediately. The program is then "unlocked" to the full version once the payment process is completed. Please follow these steps to purchase Xcalibre 4:

  1. Download the demonstration version by clicking here (10 MB), and install it on your computer. Note: if you have Windows 7, 8 or Vista, you will need to right-click and "Run as administrator."
  2. Select the appropriate license/quantity from the lists at the bottom of this page, and click "Add to Cart." Then complete your purchase.
  3. After payment is completed (that is, we receive your check/wire or run your credit card), please open the program (again, if you have Windows 7, 8 or Vista, you will need to right-click and "Run as administrator"), and click the "Unlock" button. You will then be presented with two unlock codes. Send those to ASC (contact us with the unlock codes or call 651-647-9220), along with your name and Invoice number. We will send back a key code that will unlock the program into the full version.

The demonstration version of Xcalibre 4 is available for evaluation of the program with no cost and no obligation to purchase. While limited to 50 items and 50 examinees, there is no limit on time. This makes it useful as a completely free student version. If you wish to purchase the full version at any time, simply complete Steps 2 and 3 in the list above or contact us for more information.


As of April 22, 2015 our academic licenses will no longer be available as perpetual licenses. This is due to the rising costs of maintaining technical support for these programs. Any academic licenses purchased before this date will be allowed to retain their perpetual status. Any new/additional licenses purchased thereafter, will be subject to the new policy and will be sold as 1- or 3-year licenses. No exceptions under any circumstances. If you have any questions regarding this policy, please contact us at

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