High growth city = poorer city?

I came across an intriguing new study, courtesy of the HoustonTomorrow website, which headlined it, “Fast metro growth =lower incomes: Study links poverty, growth.” The study itself, “Relationship between Growth and Prosperity in 100 Largest U.S. Metropolitan Areas,” by consulting firm Fodor & Associates, looked at the fastest-growing and slowest-growing U.S. metro areas 2000-2009, and looked at per capita income, unemployment rate, and poverty rate. It found that faster growth rates were associated with lower incomes, greater income declines, and higher poverty rates.

Charlotte-Gastonia-Concord and Raleigh-Cary were among the fastest-growing metros the study looked at – no surprise. The report’s writers say it throws some cold water on the often-stated belief on the part of many elected and business officials that growing fast is an automatic route to prosperity.
One caveat: In a quick skim of the report I didn’t see enough data to tell me whether it had taken into account the fact that many of the fastest-growing cities in the South and the West were poorer to start with, and the slower-growing cities in the North and Midwest were places with higher pay (manufacturing, unions, etc.) but less economic growth, hence less population growth. In other words, does the study show causality or just correlation? If any academics or others have time to pore through the report and offer an analysis, it would be welcome.