The California Department of Education Wants to Gauge the Difficulty

The California Department of Education wants to gauge the difficulty of a new exam by having a sample of students at a particular school take the exam. The quality of the students at the chosen school varies widely and the school administrators are allowed to choose who gets to take the exam. The administrators have a strong incentive for the school to do well on the exam. Do you think the results will represent the true ability of the students at school? What kind of bias, if any, do you think will be present? Explain.