Statistics is actually pretty hard to get right, and it is the nature of the problem space that errors aren't immediately apparent unless one actually runs anal

Statistics is actually pretty hard to get right, and it is the nature of the problem space that errors aren't immediately apparent unless one actually runs analytical regression on the algorithm to confirm it has the right "shape," which (a) can be time-consuming given the complexity of the algorithm and (b) doesn't tend to be part of unit tests because unit test doctrine is pathologically opposed to nondeterminism. (This last pert is not an unsolvable problem, and in fact random algorithms should be unit tested. But it requires the right kind of unit testing).