G'day people, i have yet another problem with my ever so growing database (access)

i have some data in a sub form (linked through a query) which has to show averages, raw data etc.

i also have to show the standard deviation of the said data, and then put all the data (raw data, averages and standard deviation) into a graphical form in access!!!

i have tried many ways of working it out but can never find the correct way to work out the nth number

please be gentle as im new to the database game

cheers

andy DZ