What is going with regional IQ and prevalence of IQ among young (school age) immigrants?
My idea is that regions with lower IQ underestimate prevalence of disability among young immigrants. The only other scenario I can think of that fits with the data is that parents of disabled immigrants tend to move to high IQ regions, but I think this is very unlikely.

A draf of my paper can be read here: https://docs.google.com/document/d/1NCdCOrF02Ljr1IEDmxIrpyKH_Vgj_4JWYIYACoa0g9U/edit?usp=sharing

P.S.: This is not a formal submission to OP.

I would like to see if this result can be replicated in countries other than Italy. Do you have some information on this ?

You noted somewhere that a "more intuitive way to estimate the bias in detecting disability is the ratio between immigrant and native disability percentage". But I will rewrite the sentence as "...in detecting disability is the ratio of immigrant to native disability percentage".

Also, I'm not sure I understand what is Ko* (disability prevalence rate not adjusted for underestimation ?). However, I don't have other comment. Overall, it's fine to me.