The document discusses calculating the difficulty index (DI) for questions in a pilot study. DI is a ratio of the number of students who correctly answered a question to the total number of students. It indicates how easy or difficult a question is. The document provides examples of calculating DI for both objective and subjective questions. Based on the DI, questions are either selected for or rejected from the final question paper. A sample data set with hypothetical student answers and calculated DIs is also included to demonstrate how questions would be evaluated.