The researchers sought to measure the effect of immigration on the native-born in 20 rich countries, taking into account differences in skills between immigrants and natives, imperfect labor markets and the size of welfare state in each country.

该研究中，研究员们设法测定了 20 个国家中移民对本国居民的影响，考虑到的因素包括了移民与本国居民的技能差异、劳动力市场尚不完善的现状、各国福利制度的规模等等。