The three school we were speaking with all seemed to have a formula to arrive at a data based needs figure. Each school came in within 10k of each other. From there they jockeyed to be the lowest (though in the end that was not the final consideration for us, we had made our decision). Frankly, I was surprised how much aid we were awarded given our family's financial profile. I was shocked actually. I expected nothing based on my tax receipts and final tuition was 1/3 the published tuition. Choate, Deerfield and Avon have HUGE endowments.