The following tables summarize the characteristics of tract categories in the MixedMetro tract classification scheme described in detail in Holloway, Wright and Ellis (2011).1 Briefly, the scheme uses population shares in six racial categories - White, Black, Latino, Asian, Native American, and Other - to classify tracts by their racial diversity (measured with scaled entropy: min=0, max=1) as follows:
Low diversity tracts: scaled entropy ≤0.3707 or largest group > 80% of tract population
High diversity tracts: scaled entropy ≥0.7414 and largest group ≤ 45% of tract population
Moderate diversity tracts: those not in the low and high diversity categories
Low and moderate diversity tracts (not high diversity) are further identified by the group with the largest share of the tract population, producing 13 potential categories: six low diversity categories identified by the largest group present (e.g. low diversity White, low diversity Black, etc); six moderate diversity categories identified by the largest group present (e.g. moderate diversity White, moderate diversity Black, etc); and one high diversity category with no largest group identified.
The summary statistics presented below describe the characteristics of these categories using the set of all tracts in the US from the 1990, 2000 and 2010 censuses normalized to 2000 tract boundaries. They exclude tracts with fewer than 50 people in them in any of these three censuses.
LDW = Low Diversity White, LDB = Low Diversity Black, LDL = Low Diversity Latino, LDA = Low Diversity Asian, LDNA = Low Diversity Native American, MDW = Moderate Diversity White, MDB = Moderate Diversity Black, MDL = Moderate Diversity Latino, MDA = Moderate Diversity Asian, MDNA = Moderate Diversity Native American, MDO = Moderate Diversity Other, HD = High Diversity
The standard deviations capture the bulk of the distributional ranges but not their full extent. This table shows the minima, maxima and several percentile values (10th, 25th, 50th, 75th, 90th) for the largest group in each category. For low and moderate diversity tracts, the largest group corresponds to the referenced group in the category name. In high diversity tracts the largest group can be any group.
In low diversity tracts, the minima and medians (p50) are high. In moderate diversity tracts, the medians are in the mid 50% to mid 60% range (near or just below the value of the minima in the equivalent low diversity category) except for moderately diverse Other tracts of which there is only one.
The minima for largest group size in moderately diverse tracts can fall below 50%, dropping to as low as 31.2%, for example, in the moderately diverse White case. These cases are relatively rare, however: in 90% of moderately diverse tracts the largest group has a 41.2% or greater share of the tract population (the 10th percentile for moderately diverse Asian (MDA) tracts), excluding the singular moderately diverse Other (MDO) tract. The 25th percentile indicates that 75% of all moderately diverse tracts (again excluding the moderately diverse Other single tract case) have at least a 45% share for the largest group.
Holloway, S. R., R. Wright, and M. Ellis. 2011. The Racially Fragmented City? Neighborhood Racial Segregation and Diversity Jointly Considered. The Professional Geographer 64 (1):63–82.↩