That is the new IEA book from Nima Sanandaji, freely available here (pdf), introduction by Tom G. Palmer. Here is one short bit:
The descendants of Scandinavian migrants in the US combine the high living standards of the US with the high levels of equality of Scandinavian countries. Median incomes of Scandinavian descendants are 20 per cent higher than average US incomes. It is true that poverty rates in Scandinavian countries are lower than in the US. However, the poverty rate among descendants of Nordic immigrants in the US today is half the average poverty rate of Americans – this has been a consistent finding for decades. In fact, Scandinavian Americans have lower poverty rates than Scandinavian citizens who have not emigrated. This suggests that pre-existing cultural norms are responsible for the low levels of poverty among Scandinavians rather than Nordic welfare states.
The book has many other points of interest.