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 […]
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 […]
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 […]
A test security plan (TSP) is a document that lays out how an assessment organization address security of its intellectual property, to protect the validity of the exam scores. If a test is compromised, the scores become meaningless, so security is obviously important. The test security plan helps an organization anticipate test security issues, establish […]
The standard error of measurement (SEM) 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 […]
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 […]
One of my graduate school mentors once said in class that there are three standard errors that everyone in the assessment or I/O Psych field needs to know: mean, error, and estimate. They are quite distinct in concept and application but easily confused by someone with minimal training. I’ve personally seen the standard error of […]
Validity, in its modern conceptualization, refers to evidence that supports our intended interpretations of test scores (see Chapter 1 of APA/AERA/NCME Standards for full treatment). Validity threats are issues that hinder the interpretations and use of scores. The word “interpretation” is key because test scores can be interpreted in different ways, including ways that are […]
One of the core concepts in psychometrics is item difficulty. This refers to the probability that examinees will get the item correct for educational/cognitive assessments or respond in the keyed direction with psychological/survey assessments (more on that later). Difficulty is important for evaluating the characteristics of an item and whether it should continue to be part of […]
It’s October 30, 2017, and collusion is all over the news today… but I want to talk about a different kind of collusion. That is, non-independent test taking. In the field of psychometric forensics, examinee collusion refers to cases where an examinee takes a test with some sort of external help in obtaining the correct […]
