Item Response Theory (IRT) is a method of scoring tests. Although classical test theory methods have been widely used for a century, IRT provides a better and more scientifically based scoring procedure. Its advantages include:
• scoring tests at the item level, giving insight into the contributions of each item on the total test score
• producing scores of both the test takers and the test items on the same scale
• fitting nonlinear logistic curves, more representative of actual test performance than classical linear statistics.