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February 24, 2011

Regression Analysis of Property Tax Assessments

A recent feature in Land Lines, a quarterly magazine from the Lincoln Institute of Land Policy, contrasts tax policies in the City of Chicago and DuPage County. Authored by the institute's visiting fellow Daniel P. McMillen, the article looks at the effects that differing assessment classifications can have on the property tax system. As he points out, inconsistencies in how property is assessed and taxed causes "resistance and resentment" among taxpayers, who may lose confidence in the system's fairness. Dr. McMillen says that DuPage assessment ratios decline uniformly according to the sales price of properties, while Cook ratios vary significantly within the lower and upper ends of the price scale. By performing various types of regression analysis -- linear, non-linear, and quantile -- he demonstrates how equity is undermined when assessments vary with sales prices, as is the case in Cook. Such variations, he writes, also make expert analysis more difficult and less precise. It is worth noting when even a top statistical analyst states that certain assessment numbers are too arbitrary to fully understand. Dr. McMillen is a professor at the Institute of Government and Public Affairs and in the Department of Economics at the University of Illinois. He is also a member of the new Tax Policy Task Force that will report to the CMAP Board while analyzing state and local tax policy issues, as recommended in the GO TO 2040 plan's Efficient Governance chapter (page 215).