The economic activity index measures average economic growth in the metropolitan area. It is computed using a dynamic factor model that includes 12 variables measuring various aspects of economic activity in the MSA. The index is calibrated to Gross Metropolitan Product (GMP) growth and variance to allow for comparison across metro areas.
For additional details, see Arias, M.A., C.S. Gascon and D.E. Rapach (2016), “Metro Business Cycles,” Journal of Urban Economics 94, 90-108, http://www.sciencedirect.com/science/article/pii/S009411901630016X.
Federal Reserve Bank of St. Louis Working Paper 2014-046C, https://research.stlouisfed.org/wp/more/2014-046.
Federal Reserve Bank of St. Louis, Economic Conditions Index for Seattle-Tacoma-Bellevue, WA (MSA) [STWAGRIDX], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/STWAGRIDX, January 19, 2018.