Entries by Nathan Thompson, PhD

MICROCAT: What was assessment like in the 1980s?

ASC has been empowering organizations to develop better assessments since 1979.  Curious as to how things were back then?  Below is a copy of our newsletter from 1988, long before the days of sharing news via email and social media!  Our platform at the time was named MICROCAT.  This later became modernized to FastTest PC […]

What is the two parameter IRT model (2PL)?

Item response theory is the predominant psychometric paradigm for mid or large scale assessment.  As noted in my introductory blog post, it is actually a family of models.  In this post, we discuss the two parameter IRT model (IRT 2PL). Consider the following 3PL equation (simplified from Hambleton & Swaminathan, 1985, Eq. 3.3).  The IRT […]

What is the three parameter IRT model (3PL)?

Item response theory (IRT) is an extremely powerful psychometric paradigm that addresses many of the inadequacies of classical test theory (CTT).  If you are new to the topic, there is a broad intro here, where you will learn that IRT is actually a family of mathematical models rather than one specific one.  Today, I’m talking […]

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What is classical item facility?

Classical test theory is a century-old paradigm for psychometrics – using quantitative and scientific processes to develop and analyze assessments to improve their quality.  (Nobody likes unfair tests!)  The most basic and frequently used item statistic from classical test theory is the P-value.  It is usually called item difficulty but is sometimes called item facility, […]

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Monte Carlo simulation in adaptive testing

Simulation studies are an essential step in the development of a computerized adaptive test (CAT) that is defensible and meets the needs of your organization or other stakeholders. There are three types of simulations: Monte Carlo, Real Data (post hoc), and Hybrid. Monte Carlo simulation is the most general-purpose approach, and the one most often […]

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What is decision consistency?

If you are involved with certification testing and are accredited by the National Commission of Certifying Agencies (NCCA), you have come across the term decision consistency.  NCCA requires you to submit a report of 11 important statistics each year, each for all active test forms.  These 11 provide a high level summary of the psychometric […]

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What is the Sympson-Hetter Item Exposure Control?

Sympson-Hetter is a method of item exposure control within the algorithm of Computerized adaptive testing (CAT).  It prevents the algorithm from over-using the best items in the pool. CAT is a powerful paradigm for delivering tests that are smarter, faster, and fairer than the traditional linear approach.  However, CAT is not without its challenges.  One is […]