Polk Progress

Polk Progress Newsletter
Economic Indicators for Polk County

Methodology

The Polk Progress Index is developed on the basis of quarterly observations of six variables. The base period for the index is the first quarter of 1992. Data are adjusted for seasonal fluctuations where appropriate.

The statistical technique of factor analysis was employed to assign weights to the observed variables and derive estimates of the underlying factor. The weights used are Taxable Sales (.18); Total Employment (.19); Home Sales (.15); Residential Electric Accounts (.17); Industrial Kilowatt Hours (.17); and Hotel/ Motel Sales (.14). The index explains 89% of the variation in the combined variables. The weights and variables are subject to future verification and modification in light of changing relationships.