violent crime generally makes it more likely to come to the attention of police than property crime,
there are a host of individual and contextual factors that may impact whether police learn of an
instance of violence. While this “dark figure” of crime problem has long been recognized in
criminology (see Mosher et al., 2011; Schwartz & Vega, 2017), official reports of crime to police
are often the only type of data used for the analysis of violence problems. In particular, place-based
police violence reduction programs, such as hot-spots policing interventions, typically rely
exclusively on police call and incident data for the identification of geographic concentrations of
violent crime and the selection of targets for extra police resources (e.g., Ratcliffe et al., 2011;
Rosenfeld et al., 2014; B. Taylor et al., 2011).
This raises important questions about whether police data alone accurately and fully identify hot
spots of violent crime activity. Are other data sources useful in understanding the nature and location
of violence? Here, we examine whether emergency medical service (EMS) data collected by the fire
department can help in identifying the location and concentration of injuries caused by violence.
Building on prior work that suggests EMS data are a complement to police data (Ariel et al., 2015;
Hibdon & Groff, 2014; Hibdon et al., 2017; Telep & Hibdon, 2017), we examine violent crime calls
to the Seattle Police Department (SPD) and EMS incidents involving violence in the city of Seattle
for a 2-year period. We assess the extent of overlap in violence concentration at the community
level, as well as at hot spots identified with each source, to better understand whether EMS data can
help identify violence potentially unreported to police. We also examine whether combining EMS
and police data results in the identification of new or different hot spots. After reviewing prior work
on the concentration of violence using police and EMS data, we describe our data, methods, and
results. We conclude with a discussion of the value of considering multiple data sources for violence
prevention efforts, whether led by police or other groups.
A series of studies over the past 3 decades demonstrate that crime, as measured by police call or
incident data, is highly concentrated at a small number of geographic locations (see Telep &
Weisburd, 2018, for a review). The consistency of crime concentration in small geographic areas
resulted in Weisburd (2015) proposing a law of crime concentration at the place, arguing that across
cities, about half of crime will be located in about 5%of places. While the definition of place varies
across studies, ranging from addresses (e.g., Sherman et al., 1989) to street segments (e.g., Weisburd
et al., 2012; Wheeler et al., 2016) and to groups of street blocks (e.g., Weisburd & Mazerolle, 2000),
the units chosen are all small. And at each level of geographic aggregation, crime is highly con-
centrated and such concentrations tend to remain stable over time (Weisburd et al., 2012).
Considering concentration at these small geographic areas has value because such locations
represent the exact contexts in which crime occurs and makes possible a deeper understanding of
the dynamics surrounding crime (Nelson et al., 2001).
Concentration of Violent Crime at Place
Research examining crime concentration using disaggregated crime types has also revealed high
levels of concentration, sometimes even stronger than overall crime. Given the emphasis of this
article, we focus in particular on violent crime. Sherman et al.’s (1989) initial work using a year of
call data in Minneapolis found violent crime calls were even more concentrated than calls overall.
While about 3.3%of addresses produced 50%of all calls, just 2.2%of addresses produced all of the
robbery calls during this period.
More recently, Braga et al. (2010) found that just 4.8%of street segments in Boston were the site
of 73.9%of all gun assaults over a 29-year period. Close to 89%of street segments and intersections
Hibdon et al. 191