Steven Reader

Detecting and analyzing clusters of low-birth weight incidence using exploratory spatial data analysis

Low birth weight incidence remains a very important public health issue, not least because of the prevalence of race as a major risk factor in low birth weight occurrence. In the United States, the rate of low birth weight incidence among African-Americans is over twice that of the rate among the white population. However, since low birth weight incidence is associated with many other risk factors, knowledge of the spatial variability of low birth weight incidence rates becomes an important aid in assessing the role of these other risk factors. This paper seeks to demonstrate the application of a linked statistical-GIS methodology for identifying statistically significant spatial clusters of abnormally high rate and low rate levels of low birth weight incidence, by race. The methodology is based on kernel density estimation with random-labeling Monte-Carlo simulation providing the inferential framework for statistical significance. Once these spatial clusters are detected, a descriptive comparison of some underlying socio-demographic variables is undertaken for different types of cluster for the two major population regions in Florida, namely the central Florida I-4 corridor, incorporating the major cities of St. Petersburg, Tampa and Orlando, and the urbanized parts of Miami-Dade, Broward and Palm Beach counties, incorporating the major cities of Miami, Ft. Lauderdale and West Palm Beach.

Spatial clustering of non-transported cardiac decedents: the results of a point pattern analysis and an inquiry into social environmental correlates

BackgroundPeople who die from heart disease at home before any attempt at transport has been made may represent missed opportunities for life-saving medical intervention. In this study, we undertook a point-pattern spatial analysis of heart disease deaths occurring before transport in a large metropolitan area to determine whether there was spatial clustering of non-transported decedents and whether there were significant differences between the clusters of non-transported cardiac decedents and the clusters of transported cardiac decedents in terms of average travel distances to nearest hospital and area socioeconomic characteristics. These analyses were adjusted for individual predictors of transport status.MethodsWe obtained transport status from the place of death variable on the death certificate. We geocoded heart disease decedents to residential street addresses using a rigorous, multistep process with 97% success. Our final study population consisted of 11,485 adults aged 25-74 years who resided in a large metropolitan area in west-central Florida and died from heart disease during 1998-2002. We conducted a kernel density analysis to identify clusters of the residential locations of cardiac decedents where there was a statistically significant excess probability of being either transported or not transported prior to death; we controlled for individual-level covariates using logistic regression-derived probability estimates.ResultsThe majority of heart disease decedents were married (53.4%), male (66.4%), white (85.6%), and aged 65-74 years at the time of death (54.7%), and a slight majority were transported prior to death (57.7%). After adjustment for individual predictors, 21 geographic clusters of non-transported heart disease decedents were observed. Contrary to our hypothesis, clusters of non-transported decedents were slightly closer to hospitals than clusters of transported decedents. The social environmental characteristics of clusters varied in the expected direction, with lower socioeconomic and household resources in the clusters of non-transported heart disease deaths.ConclusionsThese results suggest that in this large metropolitan area unfavorable household and neighborhood resources played a larger role than distance to hospital with regard to transport status of cardiac patients; more research is needed in different geographic areas of the United States and in other industrialized nations.

Using GIS to enhance programs serving emancipated youth leaving foster care

This article describes a GIS prototype designed to assist with the identification and evaluation of housing that is affordable, safe, and effective in supporting the educational goals and parental status of youth transitioning from foster care following emancipation. Spatial analysis was used to identify rental properties based on three inclusion criteria (affordability, proximity to public transportation, and proximity to grocery stores), three exclusion criteria (areas of high crime, prostitution, and sexual predator residence), and three suitability criteria (proximity to health care, mental health care, and youth serving organizations). The results were applied to four different scenarios to test the utility of the model. Of the 145 affordable rental properties, 27 met the criteria for safe and effective housing. Of these, 19 were located near bus routes with direct service to post-secondary education or vocational training programs. Only 6 were considered appropriate to meet the needs of youth who had children of their own. These outcomes highlight the complexities faced by youth when they attempt to find affordable and suitable housing following emancipation. The LEASE prototype demonstrates that spatial analysis can be a useful tool to assist with planning services for youth making the transition to independent living.

Silver Line Bus Rapid Transit in Boston, Massachusetts: Impacts on Sale Prices of Condominiums Along Washington Street

As bus rapid transit (BRT) continues to grow in popularity in the United States, a better understanding of the modes impacts on land uses and property values continues to be needed. This research sought to quantify the impacts of access to BRT stations on the sale prices of surrounding condominiums located along Washington Street in Boston, Massachusetts, where Phase 1 of the Silver Line BRT began operating in 2002. The hypothesis that the BRT stations had an impact on market value similar to light rail transit projects (considering the level and permanence of the investment) was tested with a hedonic regression methodology for estimating the impact of access to BRT stations on sale prices of condominium units. A key result was that, for condominium sales in 2007 or 2009, the BRT premium was approximately 7.6%. For condominium sales in 2000 and 2001, before the opening of the Silver Line, no sales premium existed for proximity to the corridor. These results suggest that access to high-quality transit service, not necessarily the mode itself, induces this premium. Although this study is specific to the Boston Silver Line Washington Street corridor, further research into the impacts of BRT is encouraged as a means to provide policy makers and the transit industry with the best information possible for making optimal transit investment decisions in their communities.

Rethinking Foreclosure Dynamics in a Sunbelt City: What Parcel-Level Mortgage Data Can Teach Us About Subprime Lending and Foreclosures

The dynamics of mortgage foreclosures can be studied by examining parcel-level sales and mortgage data, alongside aggregate data reporting on defaults. This research relies on such microlevel analysis to explore three issues in high-foreclosure census tracts located in Hillsborough County, Florida. First, it notes the prevalence of investor-owners in high-foreclosure areas. Second, it considers the high percentage of adjustable rate mortgages identified in these areas and the frequency with which mortgage defaults occur before interest rate adjustments take effect. Third, it suggests that high levels of investor ownership and extreme volatility of housing and mortgage markets in these neighborhoods complicate the analysis of, and solutions to, the foreclosure crisis.

Fragmentation of Florida scrub in an urban landscape

The Florida scrub community is considered a biodiversity hotspot due to the high degree of endemism and the number of species restricted to a few counties or fragments. Florida scrub habitat is officially listed as an imperiled ecoregion of global importance because it is a geographically restricted habitat with a high diversity of rare and endemic flora. This study examines landscape metrics and plant species richness of scrub in Pinellas County, which is the most densely populated county in Florida and once contained large areas of Florida scrub. Landscape metrics on scrub area, historic xeric upland area, naturally vegetated upland area within proximity, isolation indices, disturbance, and soils were collected for the 20 largest and best remaining fragments of scrub in Pinellas County from Geographic Information Systems map layers, Digital Ortho Quarter Quadrangles, and field validation. Landscape metrics were compared with three categories of species richness: scrub species richness, obligate scrub species richness, and richness of species listed as threatened or endangered. All categories of species richness in remaining Florida scrub fragments in Pinellas County were significantly associated with area of remaining scrub habitat. Site elevation was associated with obligate scrub species richness and degree of disturbance was associated with higher species richness for listed species. We conclude that large areas of scrub in higher elevated uplands and active management in the form of prescription burning will be needed to ensure the persistence of a number of endemic scrub specific species within remaining fragments.