The item discrimination parameter a is an index of item performance within the paradigm of item response theory (IRT). There are three item parameters estimated with IRT: the discrimination a, the difficulty b, and the pseudo-guessing parameter c. The item parameter that is utilized in two IRT models, 2PL and 3PL, is the IRT item […]
The item difficulty parameter from item response theory (IRT) is both a shape parameter of the item response function (IRF) but also an important way to evaluate the performance of an item in a test. Item Parameters and Models in IRT There are three item parameters estimated under dichotomous IRT: the item difficulty (b), the […]
The One Parameter Logistic Model (OPLM or 1PL or IRT 1PL) is one of the three main dichotomous models in the Item Response Theory (IRT) framework. The OPLM combines mathematical properties of the Rasch model with the flexibility of the Two Parameter Logistic Model (2PL or IRT 2PL). In the OPLM, difficulty parameters, b, are […]
A z-score measures the distance between a raw score and a mean in standard deviation units. The z-score is also known as a standard score since it enables comparing scores on various variables by standardizing the distribution of scores. It is worth mentioning that a standard normal distribution (also known as the z-score distribution or […]
The borderline group method of standard setting is one of the most common approaches to establishing a cutscore for an exam. In comparison with the item-centered standard setting methods such as modified-Angoff, Nedelsky, and Ebel, there are two well-known examinee-centered methods (Jaeger, 1989), the contrasting groups method and the borderline group method (Livingston & Zieky, 1989). […]
Item parameter drift (IPD) refers to the phenomenon in which parameter values a given test item changes over multiple testing occasions within the item response theory (IRT) framework. This phenomenon is often relevant to student progress monitoring assessments where a set of items is used several times in one year, or across years, to track […]
The concept of Speeded vs Power Test is one of the ways of differentiating psychometric or educational assessments. In the context of educational measurement and depending on the assessment goals and time constraints, tests are categorized as speeded and power. There is also the concept of a Timed test, which is really a Power test. […]
Item fit analysis is a type of model-data fit evaluation that is specific to the performance of test items. It is a very useful tool in interpreting and understanding test results, and in evaluating item performance. By implementing any psychometric model, we assume some sort of mathematical function is happening under the hood, and we […]
Educational assessment of Mathematics achievement is a critical aspect of most educational ministries and programs across the world. One might say that all subjects at school are equally important and that would be relatively true. However, Mathematics stands out amongst the remaining ones, because it is more than just an academic subject. Here are three reasons […]
Digital assessment (DA) aka e-Assessment is the delivery of assessments, tests, surveys, and other measures via digital devices such as computers, tablets, and mobile phones. It typically leverages additional technology such as the Internet or Intranets. The primary goal is to be able to develop items, publish tests, deliver tests, and provide meaningful results – […]
