If this creates jobs, I would be happy Smelling an oppurtunity
lol, jokes apart, the fact which you pointed out can be solved, there are ways to solve them mathematically. The models these people make are faboulous...
My simple single brain system can also comprehend a crude strategy that taking an average of data before event and normalising it to a same scale and comparing it to after the event should do the trick. [or in simple english, considering how much difference was before and how much difference in difference is now would do the trick]
Otherwise they must have some program designed by some smart guy with them which us mortals cant comprehend that easily. But such things are done by consultancies... I mean I do think these are done.
However if I have to make a statement from this, I would say that bards need our love, not clerics or FvS