Reviewing

One more question, is the student statistics appear on the peterson's complete statistics about student recruitment of the recent year?

You are right at this point. However, if we consider only chances of a given candidate being admitted to a given school, the calculations are useful for not the particular applicant but the admission committee. I mean, if I want to know my chance, the calculation does not give me special considerations, which loses its point... That is what makes it unlikely to give you a perfect result--the unavailability and variation of those numbers (while # of admitted students may remain relatively stable in the near future, fundings open for students vary greatly ...)

I have to say that your prior is poor. The chance of admission vary significantly between different applicants. Plus people don't get the same offers. Some have fundings but some not. In a word, the prior at the very beginning makes the calculation far from the facts.