New York City Census Tracts According to Trajectory of Shootings from 2004 to 2014

by Kevin Wolff, Sheyla Delgado and Evan Misshula
Research & Evaluation Center
February 2015

The accompanying map portrays New York City census tracts according to recent trends in gun violence. The Research & Evaluation Center calculated trend patterns based on the number of shootings each year from 2004 to 2014. The map legend indicates the trend group to which each census tract belongs.

Users may click on the individual census tracts in the map to obtain summary population statistics about that tract, including racial and ethnic diversity, poverty, unemployment, etc.

When a census tract within the five boroughs of New York City does not have shading (i.e. it is white on the map), this indicates that the tract experienced no shootings from 2004 to 2014. Areas with pale grey shading may have had a few shootings, but the number of incidents remained consistently low throughout the period. Darker grey areas experienced slightly more shootings, but the rate of shootings was often falling. Shooting rates and the trend in shootings become increasingly worse as the areas of the map become darker blue.

The groupings in the map were created using a semiparametric group-based trajectory modeling strategy incorporating shooting events in all New York census tracts. Inspired by Nagin’s trajectory modeling techniques, this approach has been used in previous research to investigate group-based differences in individual development outcomes or temporal trends in other aggregate-level events, such as homicide (Nagin, 2005; Stults, 2010). The approach uses mixture models to identify a finite set of trajectories within each neighborhood that can be categorized. The Bayesian Information Criterion (BIC) statistic is used to determine the optimal number of groups and the functional form that best fit the data using the TRAJ function is Stata 13 (Jones and Nagin, 2012).

References

Jones, Bobby, L. & Daniel S. Nagin. 2012. A Stata plugin for estimating group-based trajectory models. Sociological Methods and Research, 42(4): 608-613.

U.S. Census Bureau. American Community Survey, 2011 (5-year estimates).

Nagin, Daniel, S. 2005. Group-Based Modeling of Development. Cambridge, MA: Harvard University Press.

NYPD shooting database; Crime Data Warehouse.

Stults, Brian, J. 2010. Determinants of Chicago neighborhood homicide trajectories: 1965-1995. Homicide Studies, 14(2). 244-267.