The Spatial Concentration of Subsidized Housing - Poverty & Race ...

scale at which the impacts occur; 2) the level of subsidized housing that constitutesover-concentration; and 3) the level of poverty that constitutes over-concentration.The first is the definition of the geographic areas of concentration. Moststudies (including this one) use the census tract based primarily on both the availabilityof data at this scale but also the presumption that this is the scale at whichneighborhood impacts occur. Perhaps an impact area is one that includes multiplecensus tracts, or it could be an area smaller than a census tract such as a block group oreven a street. Impacts may not be aligned with census tracts at all. We do know fromprior impact studies that different impacts have different scales so it is important todistinguish the impacts that are significant to the policy decisions being made. In thiscase, spatial statistics could be helpful in measuring the scale of impact areasspecifically for the joint impacts of concentration of subsidized housing and poverty.The second aspect of concentration that needs attention is the definition ofwhat constitutes “too high” a level of poverty. Research studies often use 40 percentor 30 percent poverty but these have been set by the researcher to categorize the datarather than developed as a result of the study. It is possible that the actual thresholdcould be as low as 20 percent for potential negative threshold effects. This studyrelied on evidence in Galster and Quercia (2000) that there was a potential negativeimpact above 20% poverty in order to develop policy guidance on limiting additionalsubsidized housing units. This level of poverty may not be the appropriate one. Asubstantial number of subsidized units are located in census tracts with between 20126