1.41 Migration

[LordMagus]

Apologies if this has been covered, but what determines whether a given POP will move to another planet? From where I'm sitting, the process seems quite random and POPs seem quite willing to move into ghettos. That is, they will move to planets where their happiness will be lower than the planet they just left.

Case in point: This pop is taking a hit of 16% happiness when it doesn't have to. Is the only explanation that it wants to move closer to the capital planet for lower ethics divergence?

 

[The Founder]

Generally it is supposed to go to happier places. Only after a certain amount of pops have grown, do they migrate away.
They do migrate to generally happier places (like a Pacifist Empire*). However this might ignore factors like habitability, Repugnant/Charismatic and even the Ethos/Policy of the other side. It might only look at the average happiness of pops on the planet or something like that.
I have some hope that the Faction rework with 1.5 will finally clean that up.

*When I (Xenophile Collectivist) made a migration treaty with Xenophile pacifists, my pops just started going to them rather then my own planets, massively buffing thier new colonies. And I got 0 of thiers in return.