Hot-spot analysis St. Louis County foreclosures
This presentation measured the geographic distribution of single-family home foreclosures in St. Louis County, MO, 2007-2011, and analyzes patterns, identifies clusters, and investigates the underlying causes.
Published on: Mar 3, 2016
Transcripts - Hot-spot analysis St. Louis County foreclosures
Hot-spot analysis of St. Louis County, MO single-family home foreclosures, 2007-2011
Nancy Cole, GIS Certificate Student
University College, Washington University in St. Louis
The United States is currently in the throes of the deepest recession since the Great
Depression of the 1930s. Home foreclosures, driven by sub-prime lending and
adjustable-rate mortgages, have been an important factor in this recession.
Data & Methodology (continued)
Next, the raw foreclosure data was normalized by the number of single-family parcels
to yield a foreclosure rate, as follows:
St. Louis County has not escaped the
rising tide of foreclosures. Between 2007
and 2011, the number of single-family
home foreclosures were roughly double
the number for the previous five years.
2009 “Central Feature”
The county covers 524 square miles, has 371,689 land parcels – 318,937 of them
classified as single-family, and – as of 2010 – 18,747 Census blocks and 199
From 2007 through 2011,
20,465 properties were
foreclosed on; 18,699 of
them were single-family
Finally, the Getis-Ord Gi* tool was run using a Spatial Weights Matrix file, which
simplifies re-analysis using different assumptions:
1. Where have recent single-family home foreclosures occurred?
2. Does St. Louis County have statistically significant foreclosure “hot spots”?
3. Are foreclosures correlated with household income, share of college graduates,
percentage African-American residence, or the racial “diversity index”?
According to Rogers and Winter, economists at the University of Missouri at St.
Louis, real-estate researchers commonly use a “K Nearest Neighbors” weighting
structure. Rogers and Winter used 10 nearest neighbors in their own analysis of
residential foreclosures in St. Louis County.
Data & Methodology
A map of the raw data reveals that St. Louis County’s recent single-family home
foreclosures have been concentrated in the northern part of the county.
To locate statistically significant foreclosure hot spots, the raw foreclosure counts
were normalized by the number of single-family parcels to yield a foreclosure rate for
each Census block. Parcel and foreclosure data came from the county’s GIS Service
Center; block data came from the U.S. Census Bureau.
Statistically significant hot spots are concentrated in northern St. Louis County.
When compared with choropleth maps of various socioeconomic indicators by
Census tract, the hot spots are positively correlated with the percent of population
African-American and, to a lesser degree, negatively correlated with median
household income. Correlations with the percent of population holding four-year
college degrees and with USA Today’s diversity index are less evident.
First, the parcel data was prepared using the following ModelBuilder program:
Then, the foreclosure data was joined to the parcel and block data, as follows:
2012 State of the County, St. Louis County, MO, PowerPoint presentation, 2012 Strategic
Delgadillo, Lucy and Luke Erickson, “Spatial Analysis of Residential Mortgage
Default in a Metropolitan County,” Housing and Society, 2006, 33:1, 40-48.
Malkova, Olga, “Determinants of Foreclosure: A Chicago Case Study,” Senior Honors
Thesis, Economics Department, University of California, Berkeley, 2008.
Rogers, William H. and William Winter, “The Impact of Foreclosures on Neighboring
Housing Sales,” Journal of Real Estate Research, 2009, 31:4, 455-479.
Acknowledgements & Contact Information
Thanks to Bill Winston, Melisa McLean,
Adam Roberts, and Todd Swanstrom.
December 18, 2012