What I want to know (that's not answered by the above link) is, what's the math? How often does a pop have a chance to change ethos? Once a year? Once a month? Does positive divergence mean that any ethos moves will be away from the empire ethos, guaranteed (even if it's a conquered pop that already has very different ethos)? Does a more negative value mean that the pop will get more chances to change to your empire's ethos, or does it mean that you will get the same chances to change, but the probability of it working is higher?
Additionally, how do changes between the different tiers work? Does the shape of the ethos wheel matter (other than directly opposing ethos, which obviously matters)? For example, is it easier to go from militarist to Xenophobe or Spiritualist than it is to go to Xenophile or Materialist?
I've read this forum post as well which seems to be a better explanation than anything on the wiki, but there have been some major patches since then and I don't know if it's current. It also seems to suggest that fanatic pops can rotate around the wheel (like Fanatic Militarist can one-step go to Fanatic Xenophobe or Fanatic Spiritualist), which doesn't make a lot of sense to me.