Cognitive diagnostic models (CDMs) attempt to uncover latent skills or attributes that examinees must possess in order to answer test items correctly. The DINA (deterministic input, noisy "and") model is a popular CDM that has been widely used. It is shown here that a logistic version of the model can easily be fit with standard software for…

This report describes TORUS, a computer-based program for elementary school students with learning disabilities which analyzes student work samples in addition and subtraction and provides individual profiles of student misconceptions and weaknesses. Initially, work samples from 236 middle school students with learning disabilities were analyzed…