From an article about the standard of living differences between Scandinavia and the US:

A Scandinavian economist once stated to Milton Friedman: “In Scandinavia we have no poverty.” Milton Friedman replied, “That’s interesting, because in America among Scandinavians, we have no poverty either.” Indeed, the poverty rate for Americans with Swedish ancestry is only 6.7%, half the U.S average. Economists Geranda Notten and Chris de Neubourg have calculated the poverty rate in Sweden using the American poverty threshold, finding it to be an identical 6.7%.

It is important to keep cultural influences in mind when doing cross county comparisons.