Background on the Model
Pretty Robots utilized the records of 168,773 residential properties in Detroit collected during the 2014 Motor City Mapping campaign to test and train their model. The model only addresses residential properties, and only uses records where data was available for all fields. The independent variables that entered the model included: boarding, dumping, occupancy, public ownership, 2014 Tax Assessment, and 2014 Tax Foreclosure data. The end product is a percentage score that sets a fire risk level for all 168,773 property records used, based on the model created. The data used in the model was taken from the City of Detroit Assessor, the Wayne County Treasurer, as well as the Motor City Mapping campaign.
The Motor City Mapping survey collected categorical data about property use as well as condition, whereas the Assessor and Treasurer’s data is focused on ownership, value and tax status.
Motor City Mapping surveyors reported on whether or not a parcel had fire exposure. Between December 5, 2013 and July 21, 2015 they had collected information on fire exposure for over 215,283 unique properties across Detroit. This simple piece of information, indicating whether or not a property had evidence of fire exposure or not, is invaluable to calculating odds, which is a useful notion for the likelihood of an event. The odds of an event is based on a ratio; it is the probability of an event occurring divided by the probability of the event not occurring.
With odds as a baseline statistical concept and fire exposures as dependent variable, Pretty Robots was able to build contingency tables and logistic regression models in order to search for associations with other attributes within these datasets and measure the likelihood of an event.
Opportunities for Improvement
The fire risk model developed by Pretty Robots and LOVELAND can be improved through better and more frequent resurveys of Detroit property. Data from Motor City Mapping's 2013 / 2014 property survey is now more than two years old. Given the rapid rate of change in Detroit property this model would benefit greatly from updated condition information, as well as a second, citywide, snapshot of property conditions which would bring change over time into the equation. More nuanced questions of Detroit property, such as building materials, would be valuable in further development of the risk model.
The Nature of Fire in Detroit
The number of properties at high risk for fire is not static in Detroit. Fires that occur in occupied, good condition homes can lead to abandonment and leave behind a structure that is at greater risk for subsequent fires.
This was the case at 15045 Faircrest — a property that was not included in Pretty Robots’ list of high risk properties because, at the time, the property was an occupied home with no risk factors. However a suspicious fire after a break-in led to a property that is now at greater risk for subsequent fires, and is adjacent to another occupied home that is now at greater risk, too.
Despite the real progress in Detroit over the last several years since bankruptcy, there are headwinds that remain strong. The more we can do to reduce their strength, the more successful our recovery and development efforts will be, and the more equitable their distribution. Fire sets back lives, blocks, and whole neighborhoods. Together, LOVELAND and Pretty Robots believe there is much we can do to fight fires before they start.