Statistically speaking the mean/SD apply to the entire state sample. If you school has a different mean then the SD is also likely to be different. But you can go to the CAASPP site and it shows for your school how much are above average etc. This might help you get an idea on where you stand. But do not it is very coarse. It shows 50% of kids in our school exceed expectations. Makes we wonder if the standards are too low.