Title: Using Gunshot Detection Technology in High-Crime Areas. Series: Research in Progress Preview Author: Lorraine Green Mazerolle Published: June 1998 Subject: Technology in law enforcement, gun violence 8 pages 15,000 bytes ------------------------------- Figures, charts, forms, and tables are not included in this ASCII plain-text file. To view this document in its entirety, download the Adobe Acrobat graphic file available from this Web site or order a print copy from NCJRS at 800-851-3420. ------------------------------- U.S. Department of Justice Office of Justice Programs National Institute of Justice National Institute of Justice Jeremy Travis, Director Research Preview June 1998 Using Gunshot Detection Technology in High-Crime Areas A summary of a presentation by Lorraine Green Mazerolle Gunshot detection systems use acoustic sensing technology to identify, discriminate, and report gunshots to the police within seconds of the shot being fired. A gunshot detection system is comprised of sensors to detect the sound of a gunshot, transmitters to send a message to the police dispatch center, and a computer to receive and display that message. When a signal arrives at the police station, the dispatcher decides whether or not to send a unit to respond to the signal. Gunshot detection systems cannot detect shots that are fired indoors or that are blocked by a building or other obstruction. The systems may be in boxes mounted on poles, disguised as birdhouses or rooftop vents, or otherwise unobtrusively located. Researchers at the University of Cincinnati have undertaken an NIJ-sponsored study to answer three critical questions about gunshot detection technology: o How accurate are gunshot detection systems? o What impact do gunshot detection systems have on police response times? o What impact do gunshot detection systems have on police workloads? To answer these questions, the researchers undertook field trials of two systems at two sites, testing Trilon Technology's ShotSpotter [trademark] in Redwood City, California, and Alliant Techsystems' SECURES [trademark] in Dallas, Texas. How accurate are gunshot detection systems? Researchers used a test area in Redwood City, California, to determine the accuracy of Trilon Technology's ShotSpotter System. ShotSpotter uses a triangulation algorithm to pinpoint the location of the apparent gunfire and allows users to replay the sound of the gunfire noise. The test area covered about 1 square mile, which was divided into 319 sectors, each identified as either a "hot spot" (one with a relatively large amount of gunshot activity) or a "cold spot" (one with a relatively small amount of gunshot activity). On June 26 and 27, 1997, blank rounds were fired at 32 locations--22 hot spots and 10 cold spots--using one of three weapons at each site: an MP-5 assault rifle, a .38 caliber pistol, and a 12 gauge shotgun. (Note that blank shots are much more difficult to detect than live ammunition.) The researchers determined that the ShotSpotter accurately detected 80 percent of the shots fired in the field test; 72 percent of the shots were also triangulated, with a 25-foot margin of error in pinpointing the exact location of the gunshot. The type of weapon fired affected the system's ability to detect the shot: The MP-5 rounds were much more difficult for the system to detect than either the pistol or shotgun rounds. What impact do gunshot detection systems have on police response times? Researchers conducted a 2-month field trial (October 25-December 16, 1996) of the System for Effective Control for Urban Environment Security (SECURES), developed and manufactured by Alliant Techsystems, --in the Oak Cliff neighborhood of Dallas, Texas. As in Redwood City, the test area was about 1 square mile. Eighty-six SECURES units were installed on poles in the test area, primarily at intersections. Police response times to technology-generated reports of gunfire were compared to response times to citizen-generated reports both before and during the test period. For the most part, there was little difference between response times to technology-generated reports of gunfire during the test period and response times to citizen-generated reports before the test period. However, the mean response time to citizen-generated reports of gunfire during the test period (about 30 minutes) was about 30 percent less than the mean response time to technology-generated reports (about 45 minutes). Nonetheless, the overall mean response time during the test period (to the technology- and citizen-generated reports combined) was about 41 minutes, just 2 minutes longer than the mean response time before the test period (to citizen-generated reports only). Researchers concluded that using the technology did not change in any substantial way the speed with which the police responded to reports of gunfire. What impact do gunshot detection systems have on police workloads? The researchers used the data from the SECURES field test to evaluate the impact of gunshot detection systems on police workloads. During the test period, SECURES reported 182 shots fired. Dispatchers linked citizen- and technology-identified calls about random gunfire when they believed the alerts were about the same incident. During the trial period, police were dispatched to 151 random gunfire events identified only by SECURES and to 39 events identified by citizens (some of which were corroborated by SECURES). The extra 151 SECURES-dispatched events (in addition to the 39 citizen-identified dispatched events) represent a 287-percent increase in the number of police dispatches to random gunfire problems. There are two possible explanations for this significant increase in police workloads: First, gunshot detection technology may generate some false alerts. Given the design of the evaluation and the relatively early stage of this technology's development, this first possible explanation could not be explored in more detail. Second, Dallas may have a high rate of unreported gunfire, at least in the Oak Cliff neighborhood; if so, this finding could have significant ramifications for future crime analysis and crime prevention activities that seek to control the random gunfire problem in Dallas. Conclusions Gunshot detection systems have at least three potential uses: They can serve as a rapid response tool, as a problem-solving tool, and as a crime prevention tool. Three concerns arise if a gunshot detection system is intended for use as a rapid response tool (that is, to trigger immediate police response to the sound of a gunshot). First, the police department may not have a rapid response policy or the resources to implement such a policy. Second, if the tool is inaccurate, police resources may be wasted by dispatching units to false alarms. Third, a police department that is committed to community policing may prefer to focus its resources on preventive measures, rather than on rapid response measures. As a problem-solving tool, gunshot detection reports can be used with police data (e.g., citizen reports of gunfire) and physical features of a neighborhood (e.g., parks or liquor stores) to identify neighborhood hot spots. If demographics (e.g., income level or gun ownership) are considered, the data can be used to analyze various dimensions of the problem and to evaluate the effectiveness of responses to the problem. Using gunshot detection systems to prevent crime depends on whether deterrence is a factor. The police could publicize an increased likelihood of apprehension for people who fire weapons. Randomly moving the system to strategic locations will increase the range of detection coverage without greatly increasing the cost of operating the technology. The initial research into the effectiveness of gunshot detection systems is very promising, particularly in terms of the technology's usefulness in identifying and solving problems and deterring crime. As the technology develops and becomes both more accurate and more portable, these systems could prove to be highly effective tools for local police departments. ------------------------------- This Research Preview is based on a presentation by Lorraine Green Mazerolle, Ph.D., Director of the Center for Criminal Justice Research at the University of Cincinnati. This University of Cincinnati project was supported by a grant (#96-MU-MU-0018) awarded by the National Institute of Justice. ------------------------------- As part of NIJ's Research in Progress Seminar Series, Dr. Mazerolle discussed her study with an audience of researchers and criminal justice professionals and practitioners. A 60-minute VHS videotape, Using Gunshot Detection Technology in High-Crime Areas, is available for $19 ($24 in Canada and other countries). Please ask for NCJ 167027. Use the order form on the next page to obtain this videotape and any of the other tapes now available in the series. ------------------------------- Points of view in this document do not necessarily reflect the official position of the U.S. Department of Justice. FS 000201 ------------------------------- The Latest Criminal Justice Videotape Series from NIJ: Research in Progress Seminars Learn about the latest developments in criminal justice research from prominent criminal justice experts. Each 60-minute tape presents a well-known scholar discussing his or her current studies and how they relate to existing criminal justice research and includes the lecturer's responses to audience questions. In addition to Using Gunshot Detection Technology in High-Crime Areas, reported on in this Research Preview, the other tapes available in VHS format are: NCJ 152235--Alfred Blumstein, Ph.D., Professor, Carnegie Mellon University: Youth Violence, Guns, and Illicit Drug Markets. NCJ 152236--Peter W. Greenwood, Ph.D., Director, Criminal Justice Research Program, The RAND Corporation: Three Strikes, You're Out: Benefits and Costs of California's New Mandatory-Sentencing Law. NCJ 152237--Christian Pfeiffer, Ph.D., Director, Kriminologisches Forschungsinstitut Niedersachsen: Sentencing Policy and Crime Rates in Reunified Germany. NCJ 152238--Arthur L. Kellermann, M.D., M.P.H., Director, Center for Injury Control, and Associate Professor, Emory University: Understanding and Preventing Violence: A Public Health Perspective. NCJ 152692--James Inciardi, Ph.D., Director, Drug and Alcohol Center, University of Delaware: A Corrections-Based Continuum of Effective Drug Abuse Treatment. NCJ 153271--Marvin Wolfgang, Ph.D., Director, Legal Studies and Criminology, University of Pennsylvania: Crime in a Birth Cohort: A Replication in the People's Republic of China. NCJ 153730--Lawrence W. Sherman, Ph.D., Professor, University of Maryland: Reducing Gun Violence: Community Policing Against Gun Crime. NCJ 153272--Cathy Spatz Widom, Ph.D., Professor, State University of New York-Albany: The Cycle of Violence Revisited Six Years Later. NCJ 153273--Wesley Skogan, Ph.D., Professor, Northwestern University: Community Policing in Chicago: Fact or Fiction? NCJ 153850--Scott H. Decker, Ph.D., Professor, University of Missouri- St. Louis, and Susan Pennell, San Diego Association of Governments: Monitoring the Illegal Firearms Market. NCJ 154277--Terrie Moffitt, Ph.D., Professor, University of Wisconsin: Partner Violence Among Young Adults. NCJ 156923--Orlando Rodriguez, Ph.D., Director, Hispanic Research Center, Fordham University: The New Immigrant Hispanic Populations: Implications for Crime and Delinquency in the Next Decade. NCJ 156924--Robert Sampson, Ph.D., Professor, University of Chicago: Communities and Crime: A Study in Chicago. NCJ 156925--John Monahan, Ph.D., Professor, University of Virginia: Mental Illness and Violent Crime. NCJ 157643--Benjamin E. Saunders, Ph.D., and Dean G. Kilpatrick, Ph.D., Medical University of South Carolina: Prevalence and Consequences of Child Victimization: Preliminary Results from the National Survey of Adolescents. NCJ 159739--Joel H. Garner, Ph.D., Research Director, Joint Centers for Justice Studies: Use of Force By and Against the Police. NCJ 159740--Kim English, Research Director, Colorado Division of Criminal Justice: Managing Adult Sex Offenders in Community Settings: A Containment Approach. NCJ 160765--Michael Tonry, Ph.D., Professor, University of Minnesota: Ethnicity, Crime, and Immigration. NCJ 160766--David M. Kennedy, Ph.D., Professor, Harvard University: Juvenile Gun Violence and Gun Markets in Boston. NCJ 161259--Robert Crutchfield, Ph.D., Professor, University of Washington: Labor Markets, Employment, and Crime. NCJ 161836--Geoff Alpert, Ph.D., Professor, University of South Carolina: Police in Pursuit: Policy and Practice. NCJ 163056--Dan Brookoff, M.D., Ph.D., Associate Director, Medical Education, Memphis Methodist Hospital: Drug Use and Domestic Violence. NCJ 163057--Marcia Chaiken, Ph.D., Research Director of LINC, Alexandria, VA: Youth Afterschool Programs and the Role of Law Enforcement. NCJ 163058--Eric Wish, Ph.D., Director, Center for Substance Abuse Research, University of Maryland: --Dependence and Drug Treatment Needs Among Adult Arrestees. NCJ 163059--Jeffrey Fagan, Ph.D., Professor, Columbia University: Adolescent Violence: A View From the Street. NCJ 163921--Patricia Tjaden, Ph.D., Senior Researcher, Center for Policy Research: The Crime of Stalking: How Big Is the Problem? NCJ 164262--Andrew Golub, Ph.D., Principal Research Associate, National Development and Research Institutes, Inc.: Crack's Decline: Some Surprises Across U.S. Cities. NCJ 164725--Ronald Huff, Ph.D., Professor, Ohio State University: Criminal Behavior of Gang Members. NCJ 164726--James Austin, Ph.D., Executive Vice-President, National Council on Crime & Delinquency: Sentencing Guidelines: A State Perspective. NCJ 165585--Garen Wintemute, M.D., Director, Violence Prevention Research Program, University of California-Davis: Predicting Criminal Behavior Among Authorized Purchasers of Handguns. NCJ 167028--Stephen Mastrofski, Ph.D.; Roger B. Parks, Ph.D.; Albert J. Reiss, Jr., Ph.D.; and Robert E. Worden, Ph.D.: Community Policing in Action: Lessons From an Observational Study. NCJ 167029--Christian Pfeiffer, Ph.D., Director, Kriminologisches Forschungsinstitut Niedersachsen: Trends in Juvenile Violence in European Countries. NCJ 167882--Dennis Kenney, Ph.D., Research Director, Police Executive Research Forum: Crime in the Schools: A Problem-Solving Approach. NCJ 168626--Pamela Lattimore, Ph.D., and Kevin Jack Riley, Ph.D., National Institute of Justice: Homicide in Eight Cities: Trends, Contexts, and Responses. To order any of these tapes, please write to National Criminal Justice Reference Service, P.O. Box 6000, Rockville, MD 20849-6000, call 800- 851-3420, or e-mail askncjrs@ncjrs.org if you have any questions.