Beta analysis provides such a measure. Estimates for all sectors considered were obtained for the United States and its regions. To address the second objective, the appropriate statistical tests were performed. The findings indicated that for some sectors the underlying growth trends and volatilities differed in particular regions from those of the nation. This technique opens up several new lines of research.
Future research can examine the optimality of current strategies.
Also, the factors that affect alpha and beta can be analyzed, attempting to determine why they differ across regions. New York, 1991. US Department of Labor, Employment and Earnings , 1984-97.