Do Immigrants Work Harder than Native Borns?

British House of Commons Speaker John Bercow said;

'Migrants are harder workers than Britons': Speaker John Bercow says arrival of Eastern Europeans has benefited Britain
http://www.dailymail.co.uk/news/article-2336050/Migrants-harder-workers-Britons-Speaker-John-Bercow-says-arrival-Eastern-Europeans-benefited-Britain.html#ixzz2VKZxoFYQ

There are some issues that need to be addressed, I think.

1. The effects of Immigration on Economic Status of African-American Men
   A. The employment rate of black men, and particularly of low-skilled black men, fell 5.9 % between 1960 and 2000.
   B. At the same time, their incarceration rate rose 1.3%.
   C. 2.5% reduction in Wage of Black group by, 10% increase in the supply of workers.

http://onlinelibrary.wiley.com/doi/10.1111/j.1468-0335.2009.00803.x/abstract;jsessionid=B8D425F27E152A061C5E4D43028D3443.d04t01