The Spearman-Brown Prediction Formula, also known as the Spearman-Brown Prophecy Formula or Correction, is a method used in evaluating test reliability. It is based on the idea that split-half reliability has better assumptions than coefficient alpha, but only estimates reliability for a half-length test, so we need to implement a correction that steps it up […]
About Nathan Thompson, PhD
I am a psychometrician, software developer, author, and researcher, currently serving as Chief Product Officer for Assessment Systems Corporation (ASC). My mission is to elevate the profession of psychometrics by using software to automate the menial stuff like job analysis and Angoff studies, so we can focus on more innovative work. My core goal is to improve assessment throughout the world.
I was originally trained as a psychometrician, doing an undergrad at Luther College in Math/Psych/Latin and then a PhD in Psychometrics at the University of Minnesota. I then worked multiple roles in the testing industry, including item writer, test development manager, essay test marker, consulting psychometrician, software developer, project manager, and business leader.
Research and innovation are incredibly important to me. In addition to my own research, I am cofounder and Membership Director at the International Association for Computerized Adaptive Testing, You can often find me at other important conferences like ATP, ICE, CLEAR, and NCME. I've published many papers and presentations, and my favorite remains http://pareonline.net/getvn.asp?v=16&n=1.
Entries by Nathan Thompson, PhD
Artificial intelligence (AI) and machine learning (ML) have become buzzwords over the past few years. As I already wrote about, they are actually old news in the field of psychometrics. Factor analysis is a classical example of ML, and item response theory also qualifies as ML. Computerized adaptive testing is actually an application of AI […]
So, yeah, the use of “hacks” in the title is definitely on the ironic and gratuitous side, but there is still a point to be made: are you making full use of current technology to keep your tests secure? Gone are the days when you are limited to linear test forms on paper in physical […]
Computerized adaptive testing (CAT) has been around since the 1970s and is well-known for the benefits it can provide, most notably that it can reduce testing time 50-90% with no loss of measurement precision. Developing a sound, defensible CAT is not easy, but our goal is to make it as easy as possible – that […]
Simulation studies are an essential step in the development of an 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 […]
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 […]
Computerized adaptive testing (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 that it is a greedy algorithm which always selects your best items from the pool if it can. The way that CAT researchers address […]
Since the first tests were developed 2000 years ago for entry into civil service of Imperial China, test security has been a concern. The reason is quite straightforward: most threats to test security are also threats to validity, and the decisions we make with test scores could therefore be invalid, or at least suboptimal. It is […]
The standard error of measurement is one of the core concepts in psychometrics. One of the primary assumptions of any assessment is that it is accurately and consistently measuring whatever it is we want to measure. We therefore need to demonstrate that it is doing so. There are a number of ways of quantifying this, […]
The standard error of the mean is one of the three main standard errors in psychometrics and psychology. Its purpose is to help conceptualize the error in estimating the mean of some population based on a sample. The SEM is a well-known concept from the general field of statistics, used in an untold number of […]