Research

Working papers

When are D-graded neighborhoods not degraded? [PDF]

Abstract This paper explores how geography shapes the legacy of redlining, the systemic mortgage lending bias against minority us neighborhoods. On average, redlined neighborhoods lag behind adjacent, less-discriminated areas in home values, income, and racial composition. Yet, redlined neighborhoods near parks and water fare better. To help understand convergence, we inventory waterfront renovations, apply machine learning to historical imagery to track tree canopy changes, and instrument such changes exploiting tree replacements due to geographic variation in tree plagues and susceptible species. Findings suggest that enhancing waterfronts and increasing tree canopy can mitigate the long-lasting effects of institutionalized discrimination

Trees of green: constructing panels of tree canopy from aerial imagery [PDF]

Abstract This paper develops a fully-automated workflow for constructing panels of tree canopy from high-resolution multispectral imagery with limited near-infrared (NIR) training data. The proposed workflow utilizes the tree-pixel detection algorithm developed by Yang, Wu, Praun, and Ma (2009) and Bosch (2020) on a large set of U.S. urban areas but modifies it by creating automatic ground-truth masks through various visual graphics techniques that leverage modern high-resolution NIR data. By matching colors across different imagery periods, the workflow predicts tree presence in older images without NIR data, using the recent images with NIR data. Using a subset of cities that represent the different U.S. climate regions, I quantify the effectiveness of the workflow by implementing the algorithm without pre-processing in the creation of ground-truth masks, without equalizing colors across periods, and using a universal model for all areas. The comparison shows that my workflow is the option that leads to better results in terms of accuracy, recall, and precision.

Work in progress

City buzz: Face-to-Face interactions and the urban environment,with Dani Arribas-Bel, Souneil Park and Diego Puga

Abstract We measure face-to-face interactions as the coincidence in space and time of two cellphone users who have previously called each other or who start doing so after the event. We characterize the quantity, quality (network centrality of contacts met), and variety (probability that two interactions are with different contacts) of face-to-face interactions for every individual. We also characterize interactions defined by the different degrees of strength in the call network and differentiate among strong and weak ties. We show how the individual’s experienced density and other features of the urban environment affects these measures of interactions.
The Park Movement and the urban mortality transition
Abstract This project studies how the improvements in the urban physical space (the park movement) implemented between 1850 and 1950 contributed to the urban mortality transition in the City of New York. Although these landscapes modifications were motivated by incorrect science (such as reducing miasmas), they may have had positive long-term effects.
In the Shadow of the Poorhouse? The Historical Roots of American Attitudes to Poverty and Welfare , with Christian Maruthiah