The flexibility and the wealth of information provided by this program have kept it in regular use by researchers around the world

  • One, two, and three-parameter logistic models
  • Samejima's model for graded responses
  • Master's partial credit model
  • Generalized partial credit model
  • Analysis of rating scale items such as open-ended essay questions
  • Analysis of multiple-choice items
  • Differential item functioning (DIF)
  • Analysis of mixtures of item types
  • Rater's-effect analysis
  • Multiple-group polytomous item response models
  • Presentation quality IRT graphics, can be imported in Word, Access, etc.
  • Detailed online HELP documentation includes syntax and examples.


Obtaining a license for PARSCALE

  • SSI, Inc. offers academic and non-academic (production and commercial) licenses for its IRT software products.
  • Academic licenses apply to end users that intend to use the software exclusively for academic research and instruction.
  • Non-academic licenses apply to end users that intend to use the software for assessment.
  • Academic licenses for PARSCALE can be purchased by academic end users with legitimate academic email addresses via the SSI Shopping Cart.
  • Single 12 month non-academic licenses for PARSCALE can be purchased via the SSI Shopping Cart.


Free trial edition

Please note that the only limitations of the free PARSCALE trial edition are that it expires 15 days after installation and that technical support is not available.


  • Save PARSCALE4TrialSetup.exe to a temporary location.
  • Use File Explorer to open the temporary location.
  • Ensure that the saved file is approximately 19,161 KB in size. If not, please save it again.
  • Click on the Run as Administrator option on the right-click menu for PARSCALE4TrialSetup.exe.
  • Delete PARSCALE4TrialSetup.exe from the temporary location.



Product information and examples