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Reducing the robbery rate.

ALARM SYSTEMS, TIME-DELAY SAFES, and cameras are used extensively in security, but their effectiveness in reducing robbery rates has not been well documented. Only a few studies have systematically assessed security system effectiveness, producing results that do not always square with the frequency with which such equipment is used. The effectiveness of alarm systems and cameras has not been demonstrated when standard research procedures are used to assess their impact.

One study used 181 interviews with convicted armed robbers.' It found that security equipment was not particularly important to robbers when they selected a target. Of I I factors rated for importance in determining the attractiveness of a robbery target, a camera, an alarm, and a video recorder were ninth, 10th, and 11th on the list, respectively. As expected, the amount of money was the most important factor to the robbers.

A second study, conducted for Southland Corporation, found that robberies decreased in two experimental sites after cameras and silent alarms were installed, but the decrease was not large enough to be statistically significant.[2] Afterwards, security managers indicated they did not attribute the decrease in robberies to the cameras and alarms. Store clerks, however, liked the equipment primarily because it increased their feelings of safety and security.

From the point of view of the security practitioner faced with robbery prevention, these studies shed little light on ways to deter robberies. Actually, they are disturbing if installing security equipment gives employees a false sense of security.'

One difficulty with the published material is that it runs counter to the experience of many security professionals. The authors' experiences in restaurant chains throughout the country indicate security equipment is effective in reducing the incidence of robbery. Anecdotal experience, however, is not the same as well-researched, documented proof. The discrepancy between the published research and experience gave the impetus to assess the effectiveness of in-store security systems at Taco Bell restaurants.

THE SECURITY EQUIPMENT INSTALLED AT Taco Bell restaurants consisted of the following:

* Alarm system. An alarm system with hold-up buttons was located at each cash register, in the manager's office, inside the walkin cooler, in the stockroom, and near the drive-through window. The alarm system also included a passive infrared motion detector for burglary detection.

* 35 mm camera. Such a camera was in plain view of the public and could be activated by an alarm button. The alarm system also included a passive infrared motion detector for burglary detection.

* A safe. Safes had an inner compartment that operated on a 10-minute time delay. Managers were instructed to place the majority of the funds in the time-delay section of the safe after 6:00 pm and to open this section only after the restaurant was closed to count the deposit. Field security staff could not measure how often the managers used the time-delay section but believed it was not used routinely by all managers. In this study, neither the motion detector of the alarm system nor the time-delay safe would substantially affect the rate of robbery.

* Signs. Signs were posted in restaurants advising the public that the restaurant was equipped with an alarm system and a time-delay safe.

* Robbery prevention kits and training. All restaurants, whether equipped with security equipment or not, were given robbery prevention kits and training in robbery prevention.

To assess the effectiveness of this security equipment and training, the second author was given access to Taco Bell robbery files. These files contained robbery information on company-owned restaurants since 1984.

Fifty-one restaurants' robbery rates from 1984 to 1987 were analyzed. These restaurants were included on the basis of having a security system installed about halfway through this period. This way each restaurant had approximately two years of robbery data before the security system was installed and two years of data after the security system was installed.

The first robbery in the data set occurred on January 31, 1984, and the last on January 12, 1988. During this four-year period, the overall robbery rate for Taco Bell company-owned restaurants first declined, then rose dramatically, and finally declined for a net decline of 15.9 percent through December 1987, Security equipment was installed at restaurants with high robbery rates throughout this period and probably was a significant contributing factor to the overall decline.

One hundred eighty-seven robberies were recorded for these 51 restaurants during the four-year interval. Sundays and Mondays had the most robberies (each day had 32), and the least occurred on Fridays .20 robberies). The most frequently robbed restaurant suffered 12 robberies. Of the 187 robberies, 121 64,7 percent) occurred prior

[1] W. J Crow. PhD. Rosemary J. Erickson, and L. Lloyd Scott, "Set Your Sights on Preventing Retail Violence," Security, Management, September 1987, pp. 60-64.

[2] W. J. Crow and Rosemary J. Erickson, Cameras and Silent Watchman Alarms: A Study, of Their Effectiveness as a Robbery Deterrent (Jackson Hole, WY: Athena Research Press, 1984).

[3] Cameras and Silent Watchman Alarms. to installation of the alarm systems. The balance, 66 robberies, occurred after the alarms were installed (see Exhibit 1). This represents a 45.5 percent decrease in the incidence of robberies during the postinstallation period.

Further data analysis revealed that 20 restaurants (39.2 percent) did not have a single robbery after an alarm was installed; an additional 18 (35.3 percent) had only one postinstallation robbery (see Exhibit 2).

Seventy-five percent of the restaurants endured one or fewer robberies after installing an alarm system. These were all restaurants that had experienced two or more robberies in the 12 months prior to the alarm system installation. Stores suffered an average of 2.37 robberies before the alarms. The postinstallation restaurant average of 1.31 represents a drop of over one robbery for each restaurant over the course of two years.

The total sum lost during these 187 robberies was $144,902.92. An average of $847.57 was lost during preinstallation robberies, compared to an average loss of $728.17 after the alarm system and time-delay safes were installed. These figures represent a decline of $119.40 per robbery, a 14.1 percent decrease.

While this is a substantial amount, statistical analysis showed the effect to be unreliable; that is, it could not be generalized to other stores. The difficulty lies in the great variation in the amount of money lost in a robbery-from a low of $23.00 to a high of $5,711.27. With so much variability, a difference of $119.00 between the average of these two periods is quite likely-about two out of three.

One should not conclude, however, that the time-delay safes were ineffective in reducing the amount of money lost in a robbery. The data were inconclusive due to the high variability. Therefore, no firm conclusions could be drawn about the effects of time-delay safes.

The time interval in days between robberies in each restaurant was calculated for both the preinstallation and postinstallation periods and served as the primary measure of alarm system effectiveness.

The use of time intervals raises some measurement problems. The authors resolved these difficulties in such a way as to work against demonstrating the effectiveness of alarm systems. For example, the final postinstallation interval is a truncated, that is, artificially low measure.

Each final interval was calculated with an ending date of February 18, 1988 the date the data were collected. This has the effect of saying that each restaurant was robbed on this date when in reality these stores could go on for weeks, months, or even years before being robbed again. Further, the initial postinstallation interval was calculated using the alarm installation date, not the previous robbery date.

Finally, the initial preinstallation robbery interval was calculated using the first and second prealarm robbery dates so that two robberies were needed to compute one preinstallation interval. In effect, all biases in the calculation of the time intervals were done so as to yield conservative effects from the alarm systems.

Two methods were used to analyze the data concerning the interval of time between restaurant robberies, a weighted and an unweighted analysis. The first procedure found the average preinstallation robbery interval and compared it to the average postinstallation interval. This is a weighted average since restaurants that had more robberies contributed more intervals to the average.

The second procedure found the average preinstallation and postinstallation interval for each restaurant and then computed the grand average (average of the averages). This is an unweighted average since each restaurant contributed only one preinstallation and one postinstallation time interval. This second procedure controlled for the effect of restaurants suffering high robbery rates.

Both procedures yielded consistent findings. In the weighted analysis, the average robbery interval prior to the installation of the alarm systems was 133.9 days. This compares to an average postintallation robbery interval of 310.5 days, a 131.1 percent increase (see Exhibit 3).

Similarly, in the unweighted analysis the average preinstallation robbery interval was 147.5 days, while the postinstallation interval was 445.1 days (see Exhibit 4). This is an increase of 297.6 days or 201.8 percent.

Both analyses showed dramatic increases in the postinstallation time interval, but the unweighted analysis had the greatest increase. This indicates that the alarm systems tended to have their greatest impact on stores with lower initial robbery rates. It seems likely that restaurants subject to frequent robberies have other factors associated with them that diminish alarm system effectiveness. For example, these stores may be vicitm to more seasoned robbers who are undeterred by the presence of an alarm system.

In sum, the study found the number of robberies decreased 46 percent-from 121 to 66. Two separate analytical procedures were used to assess the relationship between the presence of an alarm and the frequency with which a restaurant was robbed. In both cases, an alarm system dramatically increased the interval between robberies.

The effect of an alarm system in this study was positive, and given the overall robbery rate at Taco Bell during the study, other factors such as the overall decrease in crime and change in company policy at Taco Bell probably were not responsible for the 46 percent decrease in robberies in the restaurants studied.

Results were somewhat mixed for restaurants with high robbery rates. Some restaurants showed dramatic reductions in robberies while others continued to be robbed at a high rate. This indicates alarm systems are not 100 percent effective in reducing robberies. Obviously, other factors play a role in the frequency of robberies. Overall, the results indicate an alarm system can be a useful addition to a restaurant to reduce the frequency of robberies.

The results of this study are inconsistent with the findings from the Southland study, so drawing firm conclusions from all the available empirical evidence is difficult. Intrinsic differences between the robbery profile of a convenience store and that of a fast-food restaurant may account for the disparate findings. Identifying these differences will be useful in establishing the security system that is maximally effective for both enterprises.

Security professionals in both convenience stores and fast-food restaurant chains should contribute to the research data of alarm systems' effectiveness on the rate of robberies. About the Author . . . Emil Monda, CPP, is senior director of assets protection for Taco Bell Corporation in Irvine, CA. Kirk B. O'Hara, PsyD, is senior consultant at Fuch, Cuthrell & Co. in Los Angeles.
COPYRIGHT 1990 American Society for Industrial Security
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1990 Gale, Cengage Learning. All rights reserved.

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Author:Monda, Emil; O'Hara, Kirk B.
Publication:Security Management
Date:Aug 1, 1990
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