Material related to The Theory and Application of Item Response Theory (2nd Edition)
Errata (Second Edition; Last updated on 5/10/23)
Errata (First Edition; Last updated on 5/7/20)
Software URLs and other interesting sites
Software for Item Response Theory
Software for Latent Class Analysis
The following software is available for Wintel or compatible chips
For more information on LCA software and sites click on
This link comes from a very useful site, Dr. Dayton's site:
https://education.umd.edu/directory/faculty/c-mitchell-dayton
For more information please contact R.J. De Ayala at rdeayala2@unl.edu.
For more information on our program, QQPM, please visit our site at
http://cehs.unl.edu/edpsych/quantitative-qualitative-psychometric-methods
The Four Seasons in Nebraska
Late May, 95 degrees Fahrenheit; This field has not been cultivated, the two on either side have.
Early September, 101 degrees Fahrenheit; Soybeans with corn on the horizon.
Mid November, 8 degrees Fahrenheit; wind swept. The following month we experienced wind chill temperatures of -50 degrees (F).
Early February, 35 degrees Fahrenheit; The February thaw. Winter returned with a vengance in March.
Our State Official Weather Formation
For a local picture: http://www.starcitywebcam.com/
This site maintained by:
R.J. De Ayala
Quantitative, Qualitative, and Psychometric Methods
Department of Educational Psychology
University of Nebraska
Lincoln, NE 68588
"Do not speak unless you can improve upon the silence."
- Quaker Saying