This Excel spreadsheet will help you determine if a test needs to be rescaled or curved. I have used this spreadsheet for over 9 years to determine if my exams were too difficult or if there are obvious outliers to the normal distribution. You can set the expected average score of the exam and let the program adjust grades accordingly. I have always used it to determine the true curve and the grade that is the higher between the true grade and the curved grade. This spreadsheet was developed while I was a doctoral student and is statistically sound.