Lurked
It is all very well quoting research but you need to ensure that the research is still relevant.
What you keep quoting are studies of certain demographics conducted in a certain time fame.
Now, just because the studies at that time showed x, y and a doesn't mean that x, y, and a will always be true
So, if you take a study that includes the migrants from certain EU member countries you cannot expect to automatically get the same results when include the additional migrants from other EU member countries who may also have migrants that may come to live on the UK.
Plus the the fact that the original samples on which these pieces of research were conducted will have children, will age, will require care themselves, will die etc.
So the research is a snapshot of a particular period or demonstrates trends that were occurring within a certain demographic within the timescale studied.
The research does not permit anyone to say that 'Migrants will always do X'
It just shows that between this date and that date the group of migrants that were studied did X
You cannot use that research to say that EU migrants from Bulgaria will do X because Bulgaria had not been a. Member for sufficient time within the studies. You cannot predict what migrants from Albania to the UK when Albania joins the EU will do, because Albania and Albanians are a different demographic with different national characteristics to those that the studies examined You can only say that if Albanians follow the pattern of migrants from similar countries they will do x etc.
You also have to consider the passage of time and the fact that a person's net contribution to the economy changes during their lifetime. The migrants that were studied during a productive period in which they were net contributors to the UK may no longer be net contributors and vice versa
That why I am saying that research is useful but using it in an unqualified manner and using to to state what will happen in the future is incorrect.
That's why I keep harping back to the fact that a migrant with a wife and 2 children on minimum wage is not a net contributor to the UK. However a well paid migrant in similar circumstances could be.