Our Methodology

How did we determine “priority”?

Getting legal access to intervene in a property is a significant obstacle to cleaning and greening vacant properties. We hope to reduce this barrier by helping users identify the most properties with the simplest or most attainable routes of getting access. We identify these routes by considering various factors.

1. Gun violence. We use the Philadelphia Police Department data on gun violence data.

2. Cleanliness. We use L&I data on various kinds of unclean or hazardous conditions (e.g., illegal dumping or abandoned cars).

3. Tree canopy. We use the Tree Equity Score data on tree canopy coverage.

4. In Care. We use the Pennsylvania Horticultural Society’s LandCare Program data to determine if the property is either in Community LandCare or Philadelphia LandCare initiatives. which is Philadelphia’s original cleaning and greening initiative and the basis for Dr. South’s research.

These specific datasets were chosen based on the original research and extensive stakeholder engagement. The decision tree below indicates the specific breakpoints we use in our classification.

How did we determine “access process”?

Getting legal access to intervene in a property is a significant obstacle to cleaning and greening vacant properties. We hope to reduce this barrier by helping users identify the most properties with the simplest or most attainable routes of getting access. We identify these routes by considering various factors.

1. Owner. Is it a private individual or the Philadelphia Land Bank?

2. Price. Is it expensive or affordable?

3. Conservatorship. Would qualify for Act 135 conservatorship?

We based our criteria on local law and land disposition policies, as well as the availability and applicability of data. Some of our guiding references include Grounded in Philly’s work and the Philadelphia Land Bank’s disposition policies.

Additionally, we note that our access process labels are only suggestions. Anyone using Clean & Green Philly should verify the information we have provided before acting on it. When applicable, we encourage users to seek legal advice to ensure that they are in compliance with relevant laws. Please see our legal disclaimer for more detail.

Gun Crime Calculations

It is impossible to reduce the impact of a shooting to a single statistic, and Clean & Green Philly applauds the organizations throughout our city who work to give voice to the profound effect of this epidemic on individuals, families, and communities. With this in mind, we have done our best to estimate the spatial intensity of gun violence in Philadelphia in a way that is 1) statistically rigorous and 2) as sensitive to local experience as possible. Following Dr. South’s original research, we use a kernel density estimate to calculate the intensity of gun crime at any given point in Philadelphia. Specifically, we use an adaptive bandwidth to better capture the local nuances of gun crime at small spatial scales. (For more on this, please see this memo from the data analysis team at the District Attorney’s Office.)