Entries by Nathan Thompson, PhD

Can we call it Psychometric Forensics?

An emerging sector in the field of psychometrics is the area devoted to analyzing test data to find cheaters and other illicit or invalid testing behavior. We lack a generally agreed-upon and marketable term for that sort of work, and I’d like to suggest that we use Psychometric Forensics. While research on this topic is more […]

2017 Conference on Test Security

Last week, I had the opportunity to attend the 2017 Conference on Test Security (COTS), hosted by the University of Wisconsin-Madison.  If your organization has any concerns about test security (that is, you have any sort of real stakes tied to your test!), I recommend that you attend COTS.  It has a great mix of […]

All Psychometric Models Are Wrong

The British statistician George Box is credited with the quote, “All models are wrong but some are useful.”  As psychometricians, it is important that we never forget this perspective.  We cannot be so haughty as to think that our models actually represent the true underlying phenomena and any data that does not fit nicely is just […]

Want to learn more about adaptive testing? Attend IACAT.

Computerized adaptive testing (CAT) is an incredibly important innovation in the world of assessment.  It’s a psychometric paradigm that applies machine learning principles to personalize millions and millions of assessments, from K12 education to university admissions to professional certification to employment screening to medical surveys.  While invented in the 1970s, primarily at as part of […]

What are cognitive diagnostic models?

Cognitive diagnostic models are an area of psychometric research that has seen substantial growth in the past decade, though the mathematics behind them, dating back to MacReady and Dayton (1977).  The reason that they have been receiving more attention is that in many assessment situations, a simple overall score does not serve our purposes and […]

How do I implement item response theory?

I recently received a email from a researcher that wanted to implement item response theory, but was not sure where to start.  It occurred to me that there are plenty of resources out there which describe IRT but few, if any, that provide guidance for how someone new to the topic could apply IRT.  That is, plenty […]

What is a rubric?

What is a rubric? It’s a rule for converting unstructured responses on an assessment into structured data that we can use psychometrically. Why do we need rubrics? Measurement is a quantitative endeavor.  In psychometrics, we are trying to measure things like knowledge, achievement, aptitude, or skills.  So we need a way to convert qualitative data […]