Rasch Model Workshop With Prof Bond

Day 3 The basic tenet of Rasch model posits that the probability of a specified response (e.g. right/wrong answer) is modeled as a function of person and item parameters. Specifically, in the simple Rasch model, the probability of a correct response is modeled as a logistic function of the difference between the person and item parameter. In the morning, participants were exposed to the concepts of "dochotomous" and "polytomous" measures.

As illustrated by Wikipedia, for dichotomous data such as right/wrong answers, by definition, the location of an item on a scale corresponds with the person location at which there is a 0.5 probability of a correct response to the question. The Polytomous Rasch Model is a measurement model that has potential application in any context in which the objective is to measure a trait or ability through a process in which responses to items are scored with successive integers. For example, the model is applicable to the use of Likert scales, rating scales, and to educational assessment items for which successively higher integer scores are intended to indicate increasing levels of competence or attainment. In the afternoon, participants shared their own research instruments with Prof Bond.