The thing that always bothered me about the way psychohistory was used in the books was that it all seemed to stem from Seldon's original calculations, so as history went on, errors and statistical anomalies crept in making it less and less accurate. All of which could have been solved simply by having the Foundation recalculate at certain intervals based on new data. As complex and as difficult as it might be for anyone but him, he had come up the equations himself had he not? So surely it's just a matter of leaving behind a set of instructions as to what numbers to plug into what equations and at least a basic way to interpret the results? That's kind of the whole thing about equations; once someone has cracked it, nobody else needs to understand why it works, just that it does. You don't have to be Einstein to calculate E=mc².