You can download the whole EU study mentioned in the Journal here. Here’s the summary:
If the European Union were a state in the USA it would belong to the poorest group of states. France, Italy, Great Britain and Germany have lower GDP per capita than all but four of the states in the United States. In fact, GDP per capita is lower in the vast majority of the EU-countries (EU 15) than in most of the individual American states. This puts Europeans at a level of prosperity on par with states such as Arkansas, Mississippi and West Virginia. Only the miniscule country of Luxembourg has higher per capita GDP than the average state in the USA. The results of the new study represent a grave critique of European economic policy.
Stark differences become apparent when comparing official economic statistics. Europe lags behind the USA when comparing GDP per capita and GDP growth rates. The current economic debate among EU leaders lacks an understanding of the gravity of the situation in many European countries. Structural reforms of the European economy as well as far reaching welfare reforms are well overdue. The Lisbon process lacks true impetus, nor is it sufficient to improve the economic prospects of the EU.