The multiple choice component of the exam is scored by computer, while the free response and essay portions are scored by trained Readers at the AP Reading each June. The scores on various components are weighted and combined into a raw Composite Score. The Chief Reader for each exam then decides on the grade cutoffs for that year's exam, which determine how the Composite Scores are converted into the final grades. During the process, a number of reviews and statistical analyses are performed to ensure that the grading is reliable. The overall goal is for the grades to reflect an absolute scale of performance which can be compared from year to year.